What's PHP
The PHP Hypertext Preprocessor is a programming
language that allows web developers to create dynamic content that interacts
with databases. PHP is basically used for developing web based software
applications.
What Is a Session?
A session is a logical object created by the PHP
engine to allow you to preserve data across subsequent HTTP requests.
There is only one session object available to
your PHP scripts at any time. Data saved to the session by a script can be
retrieved by the same script or another script when requested from the same
visitor.
Sessions are commonly used to store temporary
data to allow multiple PHP pages to offer a complete functional transaction for
the same visitor.
What is meant by PEAR in php?
Answer1:
PEAR is the next revolution in PHP. This
repository is bringing higher level programming to PHP. PEAR is a framework and
distribution system for reusable PHP components. It eases installation by
bringing an automated wizard, and packing the strength and experience of PHP
users into a nicely organised OOP library. PEAR also provides a command-line
interface that can be used to automatically install "packages"
Answer2:
PEAR is short for "PHP Extension and
Application Repository" and is pronounced just like the fruit. The purpose
of PEAR is to provide:
A structured library of open-sourced code for PHP
users
A system for code distribution and package
maintenance
A standard style for code written in PHP
The PHP Foundation Classes (PFC),
The PHP Extension Community Library (PECL),
A web site, mailing lists and download mirrors to
support the PHP/PEAR community
PEAR is a community-driven project with the PEAR
Group as the governing body. The project has been founded by Stig S. Bakken in
1999 and quite a lot of people have joined the project since then.
How can we know the number of days between two
given dates using PHP?
Simple arithmetic:
$date1 = date('Y-m-d');
$date2 = '2006-07-01';
$days = (strtotime() - strtotime()) / (60 * 60 *
24);
echo "Number of days since '2006-07-01':
$days";
How can we repair a MySQL table?
The syntex for repairing a mysql table is:
REPAIR TABLE tablename
REPAIR TABLE tablename QUICK
REPAIR TABLE tablename EXTENDED
This command will repair the table specified.
If QUICK is given, MySQL will do a repair of only
the index tree.
If EXTENDED is given, it will create index row by
row.
What is the difference between $message and
$$message?
Anwser 1:
$message is a simple variable whereas $$message
is a reference variable. Example:
$user = 'bob'
is equivalent to
$holder = 'user';
$$holder = 'bob';
Anwser 2:
They are both variables. But $message is a
variable with a fixed name. $$message is a variable who's name is stored in
$message. For example, if $message contains "var", $$message is the
same as $var.
What Is a Persistent Cookie?
A persistent cookie is a cookie which is stored
in a cookie file permanently on the browser's computer. By default, cookies are
created as temporary cookies which stored only in the browser's memory. When
the browser is closed, temporary cookies will be erased. You should decide when
to use temporary cookies and when to use persistent cookies based on their
differences:
- Temporary cookies can not be used for tracking long-term information.
- Persistent cookies can be used for tracking long-term information.
- Temporary cookies are safer because no programs other than the browser can access them.
- Persistent cookies are less secure because users can open cookie files see the cookie values.
What does a special set of tags <?= and
?> do in PHP?
The output is displayed directly to the browser.
How do you define a constant?
Via define() directive, like define
("MYCONSTANT", 100);
How To Write the FORM Tag Correctly for
Uploading Files?
When users clicks the submit button, files
specified in the <INPUT TYPE=FILE...> will be transferred from the
browser to the Web server. This transferring (uploading) process is controlled
by a properly written <FORM...> tag as:
<FORM ACTION=receiving.php METHOD=post ENCTYPE=multipart/form-data>
Note that you must specify METHOD as
"post" and ENCTYPE as "multipart/form-data" in order for
the uploading process to work. The following PHP code, called logo_upload.php,
shows you a complete FORM tag for file uploading:
<?php
print("<html><form action=processing_uploaded_files.php"
." method=post enctype=multipart/form-data>\n");
print("Please submit an image file a Web site logo for"
." fyicenter.com:<br>\n");
print("<input type=file name=fyicenter_logo><br>\n");
print("<input type=submit>\n");
print("</form></html>\n");
?>
What are the differences between require and
include, include_once?
Anwser 1:
require_once() and include_once() are both the
functions to include and evaluate the specified file only once. If the
specified file is included previous to the present call occurrence, it will not
be done again.
But require() and include() will do it as many
times they are asked to do.
Anwser 2:
The include_once() statement includes and
evaluates the specified file during the execution of the script. This is a
behavior similar to the include() statement, with the only difference being
that if the code from a file has already been included, it will not be included
again. The major difference between include() and require() is that in failure
include() produces a warning message whereas require() produces a fatal errors.
Anwser 3:
All three are used to an include file into the
current page.
If the file is not present, require(), calls a
fatal error, while in include() does not.
The include_once() statement includes and
evaluates the specified file during the execution of the script. This is a
behavior similar to the include() statement, with the only difference being
that if the code from a file has already been included, it will not be included
again. It des not call a fatal error if file not exists. require_once() does
the same as include_once(), but it calls a fatal error if file not exists.
Anwser 4:
File will not be included more than once. If we
want to include a file once only and further calling of the file will be
ignored then we have to use the PHP function include_once(). This will prevent
problems with function redefinitions, variable value reassignments, etc.
What is meant by urlencode and urldecode?
Anwser 1:
urlencode() returns the URL encoded version of
the given string. URL coding converts special characters into % signs followed
by two hex digits. For example: urlencode("10.00%") will return "10%2E00%25".
URL encoded strings are safe to be used as part of URLs.
urldecode() returns the URL decoded version of
the given string.
Anwser 2:
string urlencode(str) - Returns the URL encoded
version of the input string. String values to be used in URL query string need
to be URL encoded. In the URL encoded version:
Alphanumeric characters are maintained as is.
Space characters are converted to "+"
characters.
Other non-alphanumeric characters are converted
"%" followed by two hex digits representing the converted character.
string urldecode(str) - Returns the original
string of the input URL encoded string.
For example:
$discount ="10.00%";
$url =
"http://domain.com/submit.php?disc=".urlencode($discount);
echo $url;
You will get
"http://domain.com/submit.php?disc=10%2E00%25".
How To Get the Uploaded File Information in
the Receiving Script?
Once the Web server received the uploaded file,
it will call the PHP script specified in the form action attribute to process
them. This receiving PHP script can get the uploaded file information through
the predefined array called $_FILES. Uploaded file information is organized in
$_FILES as a two-dimensional array as:
- $_FILES[$fieldName]['name'] - The Original file name on the browser system.
- $_FILES[$fieldName]['type'] - The file type determined by the browser.
- $_FILES[$fieldName]['size'] - The Number of bytes of the file content.
- $_FILES[$fieldName]['tmp_name'] - The temporary filename of the file in which the uploaded file was stored on the server.
- $_FILES[$fieldName]['error'] - The error code associated with this file upload.
The $fieldName is the name used in the <INPUT
TYPE=FILE, NAME=fieldName>.
What is the difference between
mysql_fetch_object and mysql_fetch_array?
MySQL fetch object will collect first single
matching record where mysql_fetch_array will collect all matching records from
the table in an array
How can I execute a PHP script using command
line?
Just run the PHP CLI (Command Line Interface)
program and provide the PHP script file name as the command line argument. For
example, "php myScript.php", assuming "php" is the command
to invoke the CLI program.
Be aware that if your PHP script was written for
the Web CGI interface, it may not execute properly in command line environment.
I am trying to assign a variable the value of
0123, but it keeps coming up with a different number, what’s the problem?
PHP Interpreter treats numbers beginning with 0
as octal. Look at the similar PHP interview questions for more numeric
problems.
Would I use print "$a dollars" or
"{$a} dollars" to print out the amount of dollars in this example?
In this example it wouldn’t matter, since the
variable is all by itself, but if you were to print something like
"{$a},000,000 mln dollars", then you definitely need to use the
braces.
What are the different tables present in
MySQL? Which type of table is generated when we are creating a table in the
following syntax: create table employee(eno int(2),ename varchar(10))?
Total 5 types of tables we can create
1. MyISAM
2. Heap
3. Merge
4. INNO DB
5. ISAM
MyISAM is the default storage engine as of MySQL
3.23. When you fire the above create query MySQL will create a MyISAM table.
How To Create a Table?
If you want to create a table, you can run the
CREATE TABLE statement as shown in the following sample script:
<?php
include "mysql_connection.php";
$sql = "CREATE TABLE fyi_links ("
. " id INTEGER NOT NULL"
. ", url VARCHAR(80) NOT NULL"
. ", notes VARCHAR(1024)"
. ", counts INTEGER"
. ", time TIMESTAMP DEFAULT sysdate()"
. ")";
if (mysql_query($sql, $con)) {
print("Table fyi_links created.\n");
} else {
print("Table creation failed.\n");
}
mysql_close($con);
?>
Remember that mysql_query() returns TRUE/FALSE on
CREATE statements. If you run this script, you will get something like this:
Table fyi_links created.
How can we encrypt the username and password
using PHP?
Answer1
You can encrypt a password with the following
Mysql>SET PASSWORD=PASSWORD("Password");
Answer2
You can use the MySQL PASSWORD() function to
encrypt username and password. For example,
INSERT into user (password, ...) VALUES
(PASSWORD($password”)), ...);
How do you pass a variable by value?
Just like in C++, put an ampersand in front of
it, like $a = &$b
WHAT IS THE FUNCTIONALITY OF THE FUNCTIONS
STRSTR() AND STRISTR()?
string strstr ( string haystack, string needle )
returns part of haystack string from the first occurrence of needle to the end
of haystack. This function is case-sensitive.
stristr() is idential to strstr() except that it
is case insensitive.
When are you supposed to use endif to end the
conditional statement?
When the original if was followed by : and then
the code block without braces.
How can we send mail using JavaScript?
No. There is no way to send emails directly using
JavaScript.
But you can use JavaScript to execute a client
side email program send the email using the "mailto" code. Here is an
example:
function myfunction(form)
{
tdata=document.myform.tbox1.value;
location="mailto:mailid@domain.com?subject=...";
return true;
}
What is the functionality of the function
strstr and stristr?
strstr() returns part of a given string from the
first occurrence of a given substring to the end of the string. For example:
strstr("user@example.com","@") will return
"@example.com".
stristr() is idential to strstr() except that it
is case insensitive.
What is the difference between ereg_replace()
and eregi_replace()?
eregi_replace() function is identical to
ereg_replace() except that it ignores case distinction when matching alphabetic
characters.
How do I find out the number of parameters
passed into function9. ?
func_num_args() function returns the number of
parameters passed in.
What is the purpose of the following files
having extensions: frm, myd, and myi? What these files contain?
In MySQL, the default table type is MyISAM.
Each MyISAM table is stored on disk in three
files. The files have names that begin with the table name and have an
extension to indicate the file type.
The '.frm' file stores the table definition.
The data file has a '.MYD' (MYData) extension.
The index file has a '.MYI' (MYIndex) extension,
If the variable $a is equal to 5 and variable
$b is equal to character a, what’s the value of $$b?
100, it’s a reference to existing variable.
Write a query for the following question
The table tbl_sites contains the following data:
-----------------------------------------------------
Userid sitename country
------------------------------------------------------
1 sureshbabu indian
2 PHPprogrammer andhra
3 PHP.net usa
4 PHPtalk.com germany
5 MySQL.com usa
6 sureshbabu canada
7 PHPbuddy.com pakistan
8. PHPtalk.com austria
9. PHPfreaks.com sourthafrica
10. PHPsupport.net russia
11. sureshbabu australia
12. sureshbabu nepal
13. PHPtalk.com italy
Write a select query that will be displayed the
duplicated site name and how many times it is duplicated? …
SELECT sitename, COUNT(*) AS NumOccurrences
FROM tbl_sites
GROUP BY sitename HAVING COUNT(*) > 1
How To Protect Special Characters in Query
String?
If you want to include special characters like
spaces in the query string, you need to protect them by applying the
urlencode() translation function. The script below shows how to use
urlencode():
<?php
print("<html>");
print("<p>Please click the links
below"
." to submit comments about
FYICenter.com:</p>");
$comment = 'I want to say: "It\'s a good
site! :->"';
$comment = urlencode($comment);
print("<p>"
."<a
href=\"processing_forms.php?name=Guest&comment=$comment\">"
."It's an excellent
site!</a></p>");
$comment = 'This visitor said: "It\'s an
average site! :-("';
$comment = urlencode($comment);
print("<p>"
.'<a
href="processing_forms.php?'.$comment.'">'
."It's an average
site.</a></p>");
print("</html>");
?>
Are objects passed by value or by reference?
Everything is passed by value.
What are the differences between DROP a table
and TRUNCATE a table?
DROP TABLE table_name - This will delete the
table and its data.
TRUNCATE TABLE table_name - This will delete the
data of the table, but not the table definition.
What are the differences between GET and POST
methods in form submitting, give the case where we can use GET and we can use
POST methods?
Anwser 1:
When we submit a form, which has the GET method
it displays pair of name/value used in the form at the address bar of the
browser preceded by url. Post method doesn't display these values.
Anwser 2:
When you want to send short or small data, not
containing ASCII characters, then you can use GET” Method. But for long data
sending, say more then 100 character you can use POST method.
Once most important difference is when you are
sending the form with GET method. You can see the output which you are sending
in the address bar. Whereas if you send the form with POST” method then user can
not see that information.
Anwser 3:
What are "GET" and "POST"?
GET and POST are methods used to send data to the
server: With the GET method, the browser appends the data onto the URL. With
the Post method, the data is sent as "standard input."
Major Difference
In simple words, in POST method data is sent by
standard input (nothing shown in URL when posting while in GET method data is
sent through query string.
Ex: Assume we are logging in with username and
password.
GET: we are submitting a form to login.php, when
we do submit or similar action, values are sent through visible query string
(notice ./login.php?username=...&password=... as URL when executing the
script login.php) and is retrieved by login.php by $_GET['username'] and $_GET['password'].
POST: we are submitting a form to login.php, when
we do submit or similar action, values are sent through invisible standard
input (notice ./login.php) and is retrieved by login.php by $_POST['username']
and $_POST['password'].
POST is assumed more secure and we can send lot
more data than that of GET method is limited (they say Internet Explorer can
take care of maximum 2083 character as a query string).
Anwser 4:
In the get method the data made available to the
action page ( where data is received ) by the URL so data can be seen in the
address bar. Not advisable if you are sending login info like password etc. In
the post method the data will be available as data blocks and not as query
string in case of get method.
Anwser 5:
When we submit a form, which has the GET method
it pass value in the form of query string (set of name/value pair) and display
along with URL. With GET we can a small data submit from the form (a set of 255
character) whereas Post method doesn't display value with URL. It passes value
in the form of Object and we can submit large data from the form.
Anwser 6:
On the server side, the main difference between
GET and POST is where the submitted is stored. The $_GET array stores data
submitted by the GET method. The $_POST array stores data submitted by the POST
method.
On the browser side, the difference is that data
submitted by the GET method will be displayed in the browser’s address field.
Data submitted by the POST method will not be displayed anywhere on the
browser.
GET method is mostly used for submitting a small
amount and less sensitive data. POST method is mostly used for submitting a
large amount or sensitive data.
How do you call a constructor for a parent
class?
parent::constructor($value)
WHAT ARE THE DIFFERENT TYPES OF ERRORS IN PHP?
Here are three basic types of runtime errors in
PHP:
1. Notices: These are trivial, non-critical
errors that PHP encounters while executing a script - for example, accessing a
variable that has not yet been defined. By default, such errors are not
displayed to the user at all - although you can change this default behavior.
2. Warnings: These are more serious errors - for
example, attempting to include() a file which does not exist. By default, these
errors are displayed to the user, but they do not result in script termination.
3. Fatal errors: These are critical errors - for
example, instantiating an object of a non-existent class, or calling a
non-existent function. These errors cause the immediate termination of the
script, and PHP's default behavior is to display them to the user when they
take place.
Internally, these variations are represented by
twelve different error types
What’s the special meaning of __sleep and
__wakeup?
__sleep returns the array of all the variables
than need to be saved, while __wakeup retrieves them.
How can we submit a form without a submit
button?
If you don't want to use the Submit button to
submit a form, you can use normal hyper links to submit a form. But you need to
use some JavaScript code in the URL of the link. For example:
<a href="javascript:
document.myform.submit();">Submit Me</a>
Why doesn’t the following code print the
newline properly? <?php $str = ‘Hello, there.\nHow are you?\nThanks for
visiting fyicenter’; print $str; ?>
Because inside the single quotes the \n character
is not interpreted as newline, just as a sequence of two characters - \ and n.
Would you initialize your strings with single
quotes or double quotes?
Since the data inside the single-quoted string is
not parsed for variable substitution, it’s always a better idea speed-wise to
initialize a string with single quotes, unless you specifically need variable
substitution.
How can we extract string 'abc.com ' from a
string http://info@abc.com using regular expression of php?
We can use the preg_match() function with "/.*@(.*)$/" as
the regular expression pattern. For example:
preg_match("/.*@(.*)$/","http://info@abc.com",$data);
echo $data[1];
What is the difference between the functions
unlink and unset?
unlink() is a function for file system handling.
It will simply delete the file in context.
unset() is a function for variable management. It
will make a variable undefined.
How come the code works, but doesn’t for
two-dimensional array of mine?
Any time you have an array with more than one
dimension, complex parsing syntax is required. print "Contents:
{$arr[1][2]}" would’ve worked.
How can we register the variables into a
session?
session_register($session_var);
$_SESSION['var'] = 'value';
What is the difference between characters \023
and \x23?
The first one is octal 23, the second is hex 23.
With a heredoc syntax, do I get variable
substitution inside the heredoc contents?
Yes.
How can we submit form without a submit
button?
We can use a simple JavaScript code linked to an
event trigger of any form field. In the JavaScript code, we can call the
document.form.submit() function to submit the form. For example: <input
type=button value="Save"
onClick="document.form.submit()">
How can we create a database using PHP and
mysql?
We can create MySQL database with the use of
mysql_create_db($databaseName) to create a database.
How many ways we can retrieve the date in
result set of mysql using php?
As individual objects so single record or as a
set or arrays.
Can we use include ("abc.php") two
times in a php page "makeit.php"?
Yes.
For printing out strings, there are echo,
print and printf. Explain the differences.
echo is the most primitive of them, and just
outputs the contents following the construct to the screen. print is also a
construct (so parentheses are optional when calling it), but it returns TRUE on
successful output and FALSE if it was unable to print out the string. However,
you can pass multiple parameters to echo, like:
<?php echo 'Welcome ', 'to', ' ',
'fyicenter!'; ?>
and it will output the string "Welcome to
fyicenter!" print does not take multiple parameters. It is also generally
argued that echo is faster, but usually the speed advantage is negligible, and
might not be there for future versions of PHP. printf is a function, not a
construct, and allows such advantages as formatted output, but it’s the slowest
way to print out data out of echo, print and printf.
I am writing an application in PHP that
outputs a printable version of driving directions. It contains some long
sentences, and I am a neat freak, and would like to make sure that no line
exceeds 50 characters. How do I accomplish that with PHP?
On large strings that need to be formatted
according to some length specifications, use wordwrap() or chunk_split().
What’s the output of the ucwords function in
this example?
$formatted = ucwords("FYICENTER IS
COLLECTION OF INTERVIEW QUESTIONS");
print $formatted;
What will be printed is FYICENTER IS COLLECTION
OF INTERVIEW QUESTIONS.
ucwords() makes every first letter of every word
capital, but it does not lower-case anything else. To avoid this, and get a
properly formatted string, it’s worth using strtolower() first.
What’s the difference between htmlentities()
and htmlspecialchars()?
htmlspecialchars only takes care of <, >,
single quote ‘, double quote " and ampersand. htmlentities translates all
occurrences of character sequences that have different meaning in HTML.
How can we extract string "abc.com"
from a string "mailto:info@abc.com?subject=Feedback" using regular
expression of PHP?
$text = "mailto:info@abc.com?subject=Feedback";
preg_match('|.*@([^?]*)|', $text, $output);
echo $output[1];
Note that the second index of $output,
$output[1], gives the match, not the first one, $output[0].
So if md5() generates the most secure hash,
why would you ever use the less secure crc32() and sha1()?
Crypto usage in PHP is simple, but that doesn’t
mean it’s free. First off, depending on the data that you’re encrypting, you
might have reasons to store a 32-bit value in the database instead of the
160-bit value to save on space. Second, the more secure the crypto is, the
longer is the computation time to deliver the hash value. A high volume site
might be significantly slowed down, if frequent md5() generation is required.
How can we destroy the session, how can we
unset the variable of a session?
session_unregister() - Unregister a global
variable from the current session
session_unset() - Free all session variables
What are the different functions in sorting an
array?
Sorting functions in PHP:
asort()
arsort()
ksort()
krsort()
uksort()
sort()
natsort()
rsort()
How can we know the count/number of elements
of an array?
2 ways:
a) sizeof($array) - This function is an alias of
count()
b) count($urarray) - This function returns the
number of elements in an array.
Interestingly if you just pass a simple var
instead of an array, count() will return 1.
How many ways we can pass the variable through
the navigation between the pages?
At least 3 ways:
1. Put the variable into session in the first
page, and get it back from session in the next page.
2. Put the variable into cookie in the first
page, and get it back from the cookie in the next page.
3. Put the variable into a hidden form field, and
get it back from the form in the next page.
What is the maximum length of a table name, a
database name, or a field name in MySQL?
Database name: 64 characters
Table name: 64 characters
Column name: 64 characters
How many values can the SET function of MySQL
take?
MySQL SET function can take zero or more values,
but at the maximum it can take 64 values.
What are the other commands to know the
structure of a table using MySQL commands except EXPLAIN command?
DESCRIBE table_name;
How can we find the number of rows in a table
using MySQL?
Use this for MySQL
SELECT COUNT(*) FROM table_name;
What’s the difference between md5(), crc32()
and sha1() crypto on PHP?
The major difference is the length of the hash
generated. CRC32 is, evidently, 32 bits, while sha1() returns a 128 bit value,
and md5() returns a 160 bit value. This is important when avoiding collisions.
How can we find the number of rows in a result
set using PHP?
Here is how can you find the number of rows in a
result set in PHP:
$result = mysql_query($any_valid_sql,
$database_link);
$num_rows = mysql_num_rows($result);
echo "$num_rows rows found";
How many ways we can we find the current date
using MySQL?
SELECT CURDATE();
SELECT CURRENT_DATE();
SELECT CURTIME();
SELECT CURRENT_TIME();
Give the syntax of GRANT commands?
The generic syntax for GRANT is as following
GRANT [rights] on [database] TO
[username@hostname] IDENTIFIED BY [password]
Now rights can be:
a) ALL privilages
b) Combination of CREATE, DROP, SELECT, INSERT,
UPDATE and DELETE etc.
We can grant rights on all databse by usingh *.*
or some specific database by database.* or a specific table by
database.table_name.
Give the syntax of REVOKE commands?
The generic syntax for revoke is as following
REVOKE [rights] on [database] FROM
[username@hostname]
Now rights can be:
a) ALL privilages
b) Combination of CREATE, DROP, SELECT, INSERT,
UPDATE and DELETE etc.
We can grant rights on all databse by usingh *.*
or some specific database by database.* or a specific table by
database.table_name.
Answer the questions with the following
assumption
The structure of table view buyers is as follows:
+-------------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+-------------+------+-----+---------+----------------+
| user_pri_id | int(15) | | PRI | NULL | auto_increment |
| userid | varchar(10) | YES | | NULL | |
+-------------+-------------+------+-----+---------+----------------+
The value of user_pri_id of the last row is 2345.
What will happen in the following conditions?
Condition 1: Delete all the rows and insert
another row. What is the starting value for this auto incremented field
user_pri_id?
Condition 2: Delete the last row (having the
field value 2345) and insert another row. What is the value for this auto
incremented field user_pri_id?
In both conditions, the value of this auto
incremented field user_pri_id is 2346.
What is the difference between CHAR and
VARCHAR data types?
CHAR is a fixed length data type. CHAR(n) will
take n characters of storage even if you enter less than n characters to that
column. For example, "Hello!" will be stored as "Hello! "
in CHAR(10) column.
VARCHAR is a variable length data type.
VARCHAR(n) will take only the required storage for the actual number of
characters entered to that column. For example, "Hello!" will be
stored as "Hello!" in VARCHAR(10) column.
How can we encrypt and decrypt a data present
in a mysql table using mysql?
AES_ENCRYPT() and AES_DECRYPT()
Will comparison of string "10" and
integer 11 work in PHP?
Yes, internally PHP will cast everything to the
integer type, so numbers 10 and 11 will be compared.
What is the functionality of MD5 function in
PHP?
string md5(string)
It calculates the MD5 hash of a string. The hash
is a 32-character hexadecimal number.
How can I load data from a text file into a
table?
The MySQL provides a LOAD DATA INFILE command.
You can load data from a file. Great tool but you need to make sure that:
a) Data must be delimited
b) Data fields must match table columns correctly
How can we know the number of days between two
given dates using MySQL?
Use DATEDIFF()
SELECT DATEDIFF(NOW(),'2006-07-01');
How can we change the name of a column of a
table?
This will change the name of column:
ALTER TABLE table_name CHANGE old_colm_name
new_colm_name
How can we change the data type of a column of
a table?
This will change the data type of a column:
ALTER TABLE table_name CHANGE colm_name
same_colm_name [new data type]
What is the difference between GROUP BY and
ORDER BY in SQL?
To sort a result, use an ORDER BY clause.
The most general way to satisfy a GROUP BY clause
is to scan the whole table and create a new temporary table where all rows from
each group are consecutive, and then use this temporary table to discover
groups and apply aggregate functions (if any).
ORDER BY [col1],[col2],...[coln]; Tells DBMS
according to what columns it should sort the result. If two rows will hawe the
same value in col1 it will try to sort them according to col2 and so on.
GROUP BY [col1],[col2],...[coln]; Tells DBMS to
group (aggregate) results with same value of column col1. You can use
COUNT(col1), SUM(col1), AVG(col1) with it, if you want to count all items in
group, sum all values or view average.
What is meant by MIME?
Answer 1:
MIME is Multipurpose Internet Mail Extensions is
an Internet standard for the format of e-mail. However browsers also uses MIME
standard to transmit files. MIME has a header which is added to a beginning of
the data. When browser sees such header it shows the data as it would be a file
(for example image)
Some examples of MIME types:
audio/x-ms-wmp
image/png
aplication/x-shockwave-flash
Answer 2:
Multipurpose Internet Mail Extensions.
WWW's ability to recognize and handle files of
different types is largely dependent on the use of the MIME (Multipurpose
Internet Mail Extensions) standard. The standard provides for a system of
registration of file types with information about the applications needed to
process them. This information is incorporated into Web server and browser
software, and enables the automatic recognition and display of registered file
types. …
How can we know that a session is started or
not?
A session starts by session_start() function.
This session_start() is always declared in header
portion. it always declares first. then we write session_register().
What are the differences between
mysql_fetch_array(), mysql_fetch_object(), mysql_fetch_row()?
Answer 1:
mysql_fetch_array() -> Fetch a result row as a
combination of associative array and regular array.
mysql_fetch_object() -> Fetch a result row as
an object.
mysql_fetch_row() -> Fetch a result set as a
regular array().
Answer 2:
The difference between mysql_fetch_row() and
mysql_fetch_array() is that the first returns the results in a numeric array
($row[0], $row[1], etc.), while the latter returns a the results an array
containing both numeric and associative keys ($row['name'], $row['email'],
etc.). mysql_fetch_object() returns an object ($row->name, $row->email,
etc.).
If we login more than one browser windows at
the same time with same user and after that we close one window, then is the
session is exist to other windows or not? And if yes then why? If no then why?
Session depends on browser. If browser is closed
then session is lost. The session data will be deleted after session time out.
If connection is lost and you recreate connection, then session will continue
in the browser.
What are the MySQL database files stored in
system ?
Data is stored in name.myd
Table structure is stored in name.frm
Index is stored in name.myi
What is the difference between PHP4 and PHP5?
PHP4 cannot support oops concepts and Zend engine
1 is used.
PHP5 supports oops concepts and Zend engine 2 is
used.
Error supporting is increased in PHP5.
XML and SQLLite will is increased in PHP5.
Can we use include(abc.PHP) two times in a PHP
page makeit.PHP”?
Yes we can include that many times we want, but
here are some things to make sure of:
(including abc.PHP, the file names are
case-sensitive)
there shouldn't be any duplicate function names,
means there should not be functions or classes or variables with the same name
in abc.PHP and makeit.php
What are the differences between
mysql_fetch_array(), mysql_fetch_object(), mysql_fetch_row()?
mysql_fetch_array - Fetch a result row as an
associative array and a numeric array.
mysql_fetch_object - Returns an object with
properties that correspond to the fetched row and moves the internal data
pointer ahead. Returns an object with properties that correspond to the fetched
row, or FALSE if there are no more rows
mysql_fetch_row() - Fetches one row of data from
the result associated with the specified result identifier. The row is returned
as an array. Each result column is stored in an array offset, starting at
offset 0.
What is meant by nl2br()?
Anwser1:
nl2br() inserts a HTML tag <br> before all
new line characters \n in a string.
echo nl2br("god bless \n you");
output:
god bless<br>
you
How can we encrypt and decrypt a data
presented in a table using MySQL?
You can use functions: AES_ENCRYPT() and
AES_DECRYPT() like:
AES_ENCRYPT(str, key_str)
AES_DECRYPT(crypt_str, key_str)
How can I retrieve values from one database
server and store them in other database server using PHP?
For this purpose, you can first read the data
from one server into session variables. Then connect to other server and simply
insert the data into the database.
WHO IS THE FATHER OF PHP AND WHAT IS THE
CURRENT VERSION OF PHP AND MYSQL?
Rasmus Lerdorf.
PHP 5.1. Beta
MySQL 5.0
IN HOW MANY WAYS WE CAN RETRIEVE DATA IN THE
RESULT SET OF MYSQL USING PHP?
mysql_fetch_array - Fetch a result row as an
associative array, a numeric array, or both
mysql_fetch_assoc - Fetch a result row as an
associative array
mysql_fetch_object - Fetch a result row as an
object
mysql_fetch_row —- Get a result row as an
enumerated array
What are the functions for IMAP?
imap_body - Read the message body
imap_check - Check current mailbox
imap_delete - Mark a message for deletion from
current mailbox
imap_mail - Send an email message
What are encryption functions in PHP?
CRYPT()
MD5()
What is the difference between htmlentities()
and htmlspecialchars()?
htmlspecialchars() - Convert some special
characters to HTML entities (Only the most widely used)
htmlentities() - Convert ALL special characters
to HTML entities
What is the functionality of the function
htmlentities?
htmlentities() - Convert all applicable
characters to HTML entities
This function is identical to htmlspecialchars()
in all ways, except with htmlentities(), all characters which have HTML
character entity equivalents are translated into these entities.
How can we get the properties (size, type,
width, height) of an image using php image functions?
To know the image size use getimagesize()
function
To know the image width use imagesx() function
To know the image height use imagesy() function
How can we increase the execution time of a
php script?
By the use of void set_time_limit(int seconds)
Set the number of seconds a script is allowed to
run. If this is reached, the script returns a fatal error. The default limit is
30 seconds or, if it exists, the max_execution_time value defined in the
php.ini. If seconds is set to zero, no time limit is imposed.
When called, set_time_limit() restarts the
timeout counter from zero. In other words, if the timeout is the default 30
seconds, and 25 seconds into script execution a call such as set_time_limit(20)
is made, the script will run for a total of 45 seconds before timing out.
HOW CAN WE TAKE A BACKUP OF A MYSQL TABLE AND
HOW CAN WE RESTORE IT?
Answer 1:
Create a full backup of your database: shell>
mysqldump tab=/path/to/some/dir opt db_name
Or: shell> mysqlhotcopy db_name
/path/to/some/dir
The full backup file is just a set of SQL
statements, so restoring it is very easy:
shell> mysql "."Executed";
Answer 2:
To backup: BACKUP TABLE tbl_name TO /path/to/backup/directory
’ To restore: RESTORE TABLE tbl_name FROM
/path/to/backup/directory
mysqldump: Dumping Table Structure and Data
Utility to dump a database or a collection of
database for backup or for transferring the data to another SQL server (not
necessarily a MySQL server). The dump will contain SQL statements to create the
table and/or populate the table.
-t, no-create-info
Don't write table creation information (the
CREATE TABLE statement).
-d, no-data
Don't write any row information for the table.
This is very useful if you just want to get a dump of the structure for a
table!
How to set cookies?
setcookie('variable','value','time')
;
variable - name of the cookie variable
value - value of the cookie variable
time - expiry time
Example: setcookie('Test',$i,time()+3600);
Test - cookie variable name
$i - value of the variable 'Test'
time()+3600 - denotes that the cookie will expire
after an one hour
How to reset/destroy a cookie
Reset a cookie by specifying expire time in the
past:
Example: setcookie('Test',$i,time()-3600); //
already expired time
Reset a cookie by specifying its name only
Example: setcookie('Test');
WHAT TYPES OF IMAGES THAT PHP SUPPORTS?
Using imagetypes() function to find out what
types of images are supported in your PHP engine.
imagetypes() - Returns the image types supported.
This function returns a bit-field corresponding
to the image formats supported by the version of GD linked into PHP. The
following bits are returned, IMG_GIF | IMG_JPG | IMG_PNG | IMG_WBMP | IMG_XPM.
CHECK IF A VARIABLE IS AN INTEGER IN
JAVASCRIPT
var myValue =9.8;
if(parseInt(myValue)== myValue)
alert('Integer');
else
alert('Not an integer');
Tools used for drawing ER diagrams.
Case Studio
Smart Draw
How can I know that a variable is a number or
not using a JavaScript?
Answer 1:
bool is_numeric( mixed var)
Returns TRUE if var is a number or a numeric
string, FALSE otherwise.
Answer 2:
Definition and Usage
The isNaN() function is used to check if a value
is not a number.
Syntax
isNaN(number)
Parameter Description
number Required. The value to be tested
How can we submit from without a submit
button?
Trigger the JavaScript code on any event ( like
onSelect of drop down list box, onfocus, etc ) document.myform.submit(); This
will submit the form.
How many ways can we get the value of current
session id?
session_id() returns the session id for the current
session.
How can we destroy the cookie?
Set the cookie with a past expiration time.
What are the current versions of Apache, PHP,
and MySQL?
PHP: PHP 5.1.2
MySQL: MySQL 5.1
Apache: Apache 2.1
What are the reasons for selecting LAMP
(Linux, Apache, MySQL, Php) instead of combination of other software programs,
servers and operating systems?
All of those are open source resource. Security
of linux is very very more than windows. Apache is a better server that IIS
both in functionality and security. Mysql is world most popular open source
database. Php is more faster that asp or any other scripting language.
What are the features and advantages of OBJECT
ORIENTED PROGRAMMING?
One of the main advantages of OO programming is
its ease of modification; objects can easily be modified and added to a system
there by reducing maintenance costs. OO programming is also considered to be
better at modeling the real world than is procedural programming. It allows for
more complicated and flexible interactions. OO systems are also easier for
non-technical personnel to understand and easier for them to participate in the
maintenance and enhancement of a system because it appeals to natural human
cognition patterns. For some systems, an OO approach can speed development time
since many objects are standard across systems and can be reused. Components
that manage dates, shipping, shopping carts, etc. can be purchased and easily
modified for a specific system.
What is the use of friend function?
Friend functions
Sometimes a function is best shared among a
number of different classes. Such functions can be declared either as member
functions of one class or as global functions. In either case they can be set
to be friends of other classes, by using a friend specifier in the class that
is admitting them. Such functions can use all attributes of the class which
names them as a friend, as if they were themselves members of that class.
A friend declaration is essentially a prototype
for a member function, but instead of requiring an implementation with the name
of that class attached by the double colon syntax, a global function or member
function of another class provides the match.
class mylinkage
{
private:
mylinkage * prev;
mylinkage * next;
protected:
friend void set_prev(mylinkage* L, mylinkage* N);
void set_next(mylinkage* L);
public:
mylinkage * succ();
mylinkage * pred();
mylinkage();
};
void mylinkage::set_next(mylinkage* L) { next =
L; }
void set_prev(mylinkage * L, mylinkage * N ) {
N->prev = L; }
Friends in other classes
It is possible to specify a member function of
another class as a friend as follows:
class C
{
friend int B::f1();
};
class B
{
int f1();
};
It is also possible to specify all the functions
in another class as friends, by specifying the entire class as a friend.
class A
{
friend class B;
};
Friend functions allow binary operators to be
defined which combine private data in a pair of objects. This is particularly
powerful when using the operator overloading features of C++. We will return to
it when we look at overloading.
How can we get second of the current time
using date function?
$second = date("s");
What is the maximum size of a file that can be
uploaded using PHP and how can we change this?
You can change maximum size of a file set
upload_max_filesize variable in php.ini file
How can I make a script that can be bilingual
(supports English, German)?
You can change charset variable in above line in
the script to support bilanguage.
What are the difference between abstract class
and interface?
Abstract class: abstract classes are the class
where one or more methods are abstract but not necessarily all method has to be
abstract. Abstract methods are the methods, which are declare in its class but
not define. The definition of those methods must be in its extending class.
Interface: Interfaces are one type of class where
all the methods are abstract. That means all the methods only declared but not
defined. All the methods must be define by its implemented class.
What are the advantages of stored procedures,
triggers, indexes?
A stored procedure is a set of SQL commands that
can be compiled and stored in the server. Once this has been done, clients
don't need to keep re-issuing the entire query but can refer to the stored
procedure. This provides better overall performance because the query has to be
parsed only once, and less information needs to be sent between the server and
the client. You can also raise the conceptual level by having libraries of
functions in the server. However, stored procedures of course do increase the
load on the database server system, as more of the work is done on the server
side and less on the client (application) side. Triggers will also be
implemented. A trigger is effectively a type of stored procedure, one that is
invoked when a particular event occurs. For example, you can install a stored
procedure that is triggered each time a record is deleted from a transaction
table and that stored procedure automatically deletes the corresponding
customer from a customer table when all his transactions are deleted. Indexes
are used to find rows with specific column values quickly. Without an index,
MySQL must begin with the first row and then read through the entire table to
find the relevant rows. The larger the table, the more this costs. If the table
has an index for the columns in question, MySQL can quickly determine the
position to seek to in the middle of the data file without having to look at
all the data. If a table has 1,000 rows, this is at least 100 times faster than
reading sequentially. If you need to access most of the rows, it is faster to
read sequentially, because this minimizes disk seeks.
What is maximum size of a database in mysql?
If the operating system or filesystem places a
limit on the number of files in a directory, MySQL is bound by that constraint.
The efficiency of the operating system in handling large numbers of files in a
directory can place a practical limit on the number of tables in a database. If
the time required to open a file in the directory increases significantly as
the number of files increases, database performance can be adversely affected.
The amount of available disk space limits the
number of tables.
MySQL 3.22 had a 4GB (4 gigabyte) limit on table
size. With the MyISAM storage engine in MySQL 3.23, the maximum table size was
increased to 65536 terabytes (2567 – 1 bytes). With this larger allowed table
size, the maximum effective table size for MySQL databases is usually
determined by operating system constraints on file sizes, not by MySQL internal
limits.
The InnoDB storage engine maintains InnoDB tables
within a tablespace that can be created from several files. This allows a table
to exceed the maximum individual file size. The tablespace can include raw disk
partitions, which allows extremely large tables. The maximum tablespace size is
64TB.
The following table lists some examples of
operating system file-size limits. This is only a rough guide and is not
intended to be definitive. For the most up-to-date information, be sure to
check the documentation specific to your operating system.
Operating System File-size Limit
Linux 2.2-Intel 32-bit 2GB (LFS: 4GB)
Linux 2.4+ (using ext3 filesystem) 4TB
Solaris 9/10 16TB
NetWare w/NSS filesystem 8TB
Win32 w/ FAT/FAT32 2GB/4GB
Win32 w/ NTFS 2TB (possibly larger)
MacOS X w/ HFS+ 2TB
Explain normalization concept?
The normalization process involves getting our
data to conform to three progressive normal forms, and a higher level of
normalization cannot be achieved until the previous levels have been achieved
(there are actually five normal forms, but the last two are mainly academic and
will not be discussed).
First Normal
Form
The First Normal Form (or 1NF) involves removal
of redundant data from horizontal rows. We want to ensure that there is no
duplication of data in a given row, and that every column stores the least
amount of information possible (making the field atomic).
Second Normal
Form
Where the First Normal Form deals with redundancy
of data across a horizontal row, Second Normal Form (or 2NF) deals with
redundancy of data in vertical columns. As stated earlier, the normal forms are
progressive, so to achieve Second Normal Form, your tables must already be in
First Normal Form.
Third Normal
Form
I have a confession to make; I do not often use
Third Normal Form. In Third Normal Form we are looking for data in our tables
that is not fully dependant on the primary key, but dependant on another value
in the table
What’s the difference between accessing a
class method via -> and via ::?
:: is allowed to access methods that can perform
static operations, i.e. those, which do not require object initialization.
What are the advantages and disadvantages of
CASCADE STYLE SHEETS?
External Style Sheets
Advantages
Can control styles for multiple documents at once
Classes can be created for use on multiple HTML element types in many documents
Selector and grouping methods can be used to apply styles under complex
contexts
Disadvantages
An extra download is required to import style
information for each document The rendering of the document may be delayed
until the external style sheet is loaded Becomes slightly unwieldy for small
quantities of style definitions
Embedded Style Sheets
Advantages
Classes can be created for use on multiple tag
types in the document Selector and grouping methods can be used to apply styles
under complex contexts No additional downloads necessary to receive style
information
Disadvantage
This method can not control styles for multiple
documents at once
Inline Styles
Advantages
Useful for small quantities of style definitions
Can override other style specification methods at the local level so only
exceptions need to be listed in conjunction with other style methods
Disadvantages
Does not distance style information from content
(a main goal of SGML/HTML) Can not control styles for multiple documents at
once Author can not create or control classes of elements to control multiple
element types within the document Selector grouping methods can not be used to
create complex element addressing scenarios
What type of inheritance that php supports?
In PHP an extended class is always dependent on a
single base class, that is, multiple inheritance is not supported. Classes are
extended using the keyword 'extends'.
How can increase the performance of MySQL
select query?
We can use LIMIT to stop MySql for further search
in table after we have received our required no. of records, also we can use
LEFT JOIN or RIGHT JOIN instead of full join in cases we have related data in
two or more tables.
How can we change the name of a column of a
table?
MySQL query to rename table: RENAME TABLE
tbl_name TO new_tbl_name
or,
ALTER TABLE tableName CHANGE OldName newName.
When you want to show some part of a text
displayed on an HTML page in red font color? What different possibilities are
there to do this? What are the advantages/disadvantages of these methods?
There are 2 ways to show some part of a text in
red:
1. Using HTML tag <font
color="red">
2. Using HTML tag <span style="color:
red">
When viewing an HTML page in a Browser, the
Browser often keeps this page in its cache. What can be possible
advantages/disadvantages of page caching? How can you prevent caching of a
certain page (please give several alternate solutions)?
When you use the metatag in the header section at
the beginning of an HTML Web page, the Web page may still be cached in the
Temporary Internet Files folder.
A page that Internet Explorer is browsing is not
cached until half of the 64 KB buffer is filled. Usually, metatags are inserted
in the header section of an HTML document, which appears at the beginning of
the document. When the HTML code is parsed, it is read from top to bottom. When
the metatag is read, Internet Explorer looks for the existence of the page in
cache at that exact moment. If it is there, it is removed. To properly prevent
the Web page from appearing in the cache, place another header section at the
end of the HTML document. For example:
What are the different ways to login to a
remote server? Explain the means, advantages and disadvantages?
There is at least 3 ways to logon to a remote
server:
Use ssh or telnet if you concern with security
You can also use rlogin to logon to a remote
server.
Please give a regular expression (preferably
Perl/PREG style), which can be used to identify the URL from within a HTML link
tag.
Try this: /href="([^"]*)"/i
How can I use the COM components in php?
The COM class provides a framework to integrate
(D)COM components into your PHP scripts.
string COM::COM( string module_name [, string
server_name [, int codepage]]) - COM class constructor.
Parameters:
module_name: name or class-id of the requested
component.
server_name: name of the DCOM server from which
the component should be fetched. If NULL, localhost is assumed. To allow DCOM
com, allow_dcom has to be set to TRUE in php.ini.
codepage - specifies the codepage that is used to
convert php-strings to unicode-strings and vice versa. Possible values are
CP_ACP, CP_MACCP, CP_OEMCP, CP_SYMBOL, CP_THREAD_ACP, CP_UTF7 and CP_UTF8.
Usage:
$word->Visible = 1; //open an empty document
$word->Documents->Add(); //do some weird
stuff
$word->Selection->TypeText("This is a
test…");
$word->Documents[1]->SaveAs("Useless
test.doc"); //closing word
$word->Quit(); //free the object
$word->Release();
$word = null;
How many ways we can give the output to a
browser?
HTML output
PHP, ASP, JSP, Servlet Function
Script Language output Function
Different Type of embedded Package to output to a
browser
What is the default session time in php and
how can I change it?
The default session time in php is until closing
of browser
What changes I have to do in php.ini file for
file uploading?
Make the following line uncomment like:
; Whether to allow HTTP file uploads.
file_uploads = On
; Temporary directory for HTTP uploaded files
(will use system default if not
; specified).
upload_tmp_dir = C:\apache2triad\temp
; Maximum allowed size for uploaded files.
upload_max_filesize = 2M
How can I set a cron and how can I execute it
in Unix, Linux, and windows?
Cron is very simply a Linux module that allows
you to run commands at predetermined times or intervals. In Windows, it's
called Scheduled Tasks. The name Cron is in fact derived from the same word
from which we get the word chronology, which means order of time.
The easiest way to use crontab is via the crontab
command.
# crontab
This command 'edits' the crontab. Upon employing
this command, you will be able to enter the commands that you wish to run. My
version of
Linux uses the text editor vi. You can find
information on using vi here.
The syntax of this file is very important – if
you get it wrong, your crontab will not function properly. The syntax of the
file should be as follows:
minutes hours day_of_month month day_of_week
command
All the variables, with the exception of the
command itself, are numerical constants. In addition to an asterisk (*), which
is a wildcard that allows any value, the ranges permitted for each field are as
follows:
Minutes: 0-59
Hours: 0-23
Day_of_month: 1-31
Month: 1-12
Weekday: 0-6
We can also include multiple values for each
entry, simply by separating each value with a comma.
command can be any shell command and, as we will
see momentarily, can also be used to execute a Web document such as a PHP file.
So, if we want to run a script every Tuesday
morning at 8:15 AM, our mycronjob file will contain the following content on a
single line:
15 8 * * 2 /path/to/scriptname
This all seems simple enough, right? Not so fast!
If you try to run a PHP script in this manner, nothing will happen (barring
very special configurations that have PHP compiled as an executable, as opposed
to an Apache module). The reason is that, in order for PHP to be parsed, it
needs to be passed through Apache. In other words, the page needs to be called
via a browser or other means of retrieving
Web content. For our purposes, I'll assume that
your server configuration includes wget, as is the case with most default
configurations. To test your configuration, log in to shell. If you're using an
RPM-based system (e.g. Redhat or Mandrake), type the following:
# wget help
If you are greeted with a wget package
identification, it is installed in your system.
You could execute the PHP by invoking wget on the
URL to the page, like so:
# wget http://www.example.com/file.php
Now, let's go back to the mailstock.php file we
created in the first part of this article. We saved it in our document root, so
it should be accessible via the Internet. Remember that we wanted it to run at
4PM Eastern time, and send you your precious closing bell report? Since I'm
located in the Eastern timezone, we can go ahead and set up our crontab to use
4:00, but if you live elsewhere, you might have to compensate for the time
difference when setting this value.
This is what my crontab will look like:
0 4 * * 1,2,3,4,5 wget
http://www.example.com/mailstock.php
Steps for the payment gateway processing?
An online payment gateway is the interface
between your merchant account and your Web site. The online payment gateway
allows you to immediately verify credit card transactions and authorize funds
on a customer's credit card directly from your Web site. It then passes the
transaction off to your merchant bank for processing, commonly referred to as
transaction batching
How many ways I can redirect a PHP page?
Here are the possible ways of php page
redirection.
1. Using Java script:
'; echo
'window.location.href="'.$filename.'";'; echo ''; echo ''; echo '';
echo ''; } } redirect('http://maosjb.com'); ?>
2. Using php function:
header("Location:http://maosjb.com ");
List out different arguments in PHP header
function?
void header ( string string [, bool replace [,
int http_response_code]])
What type of headers have to be added in the
mail function to attach a file?
$boundary = '--' . md5( uniqid ( rand() ) );
$headers = "From: \"Me\"\n";
$headers .= "MIME-Version: 1.0\n";
$headers .= "Content-Type: multipart/mixed;
boundary=\"$boundary\"";
How to store the uploaded file to the final
location?
move_uploaded_file ( string filename, string
destination)
This function checks to ensure that the file
designated by filename is a valid upload file (meaning that it was uploaded via
PHP's HTTP POST upload mechanism). If the file is valid, it will be moved to
the filename given by destination.
If filename is not a valid upload file, then no
action will occur, and move_uploaded_file() will return FALSE.
If filename is a valid upload file, but cannot be
moved for some reason, no action will occur, and move_uploaded_file() will
return FALSE. Additionally, a warning will be issued.
What is the difference between Reply-to and
Return-path in the headers of a mail function?
Reply-to: Reply-to is where to delivery the reply
of the mail.
Return-path: Return path is when there is a mail
delivery failure occurs then where to delivery the failure notification.
Explain about Type Juggling in php?
PHP does not require (or support) explicit type
definition in variable declaration; a variable's type is determined by the
context in which that variable is used. That is to say, if you assign a string
value to variable $var, $var becomes a string. If you then assign an integer
value to $var, it becomes an integer.
An example of PHP's automatic type conversion is
the addition operator '+'. If any of the operands is a float, then all operands
are evaluated as floats, and the result will be a float. Otherwise, the
operands will be interpreted as integers, and the result will also be an
integer. Note that this does NOT change the types of the operands themselves;
the only change is in how the operands are evaluated.
$foo += 2; // $foo is now an integer (2)
$foo = $foo + 1.3; // $foo is now a float (3.3)
$foo = 5 + "10 Little Piggies"; // $foo
is integer (15)
$foo = 5 + "10 Small Pigs"; // $foo is
integer (15)
If the last two examples above seem odd, see
String conversion to numbers.
If you wish to change the type of a variable, see
settype().
If you would like to test any of the examples in
this section, you can use the var_dump() function.
Note: The behavior of an automatic conversion to
array is currently undefined.
Since PHP (for historical reasons) supports
indexing into strings via offsets using the same syntax as array indexing, the
example above leads to a problem: should $a become an array with its first
element being "f", or should "f" become the first character
of the string $a? The current versions of PHP interpret the second assignment
as a string offset identification, so $a becomes "f", the result of
this automatic conversion however should be considered undefined. PHP 4
introduced the new curly bracket syntax to access characters in string, use
this syntax instead of the one presented above:
How can I embed a java programme in php file
and what changes have to be done in php.ini file?
There are two possible ways to bridge PHP and
Java: you can either integrate PHP into a Java Servlet environment, which is
the more stable and efficient solution, or integrate Java support into PHP. The
former is provided by a SAPI module that interfaces with the Servlet server,
the latter by this Java extension.
The Java extension provides a simple and
effective means for creating and invoking methods on Java objects from PHP. The
JVM is created using JNI, and everything runs in-process.
Example Code:
getProperty('java.version') . ''; echo 'Java
vendor=' . $system->getProperty('java.vendor') . ''; echo 'OS=' .
$system->getProperty('os.name') . ' ' .
$system->getProperty('os.version') . ' on ' .
$system->getProperty('os.arch') . ' '; // java.util.Date example $formatter
= new Java('java.text.SimpleDateFormat', "EEEE, MMMM dd, yyyy 'at' h:mm:ss
a zzzz"); echo $formatter->format(new Java('java.util.Date')); ?>
The behaviour of these functions is affected by
settings in php.ini.
Table 1. Java configuration options
Name
Default
Changeable
java.class.path
NULL
PHP_INI_ALL
Name Default Changeable
java.home
NULL
PHP_INI_ALL
java.library.path
NULL
PHP_INI_ALL
java.library
JAVALIB
PHP_INI_ALL
How To Turn On the Session Support?
The session support can be turned on
automatically at the site level, or manually in each PHP page script:
- Turning on session support automatically at the site level: Set session.auto_start = 1 in php.ini.
- Turning on session support manually in each page script: Call session_start() funtion.
Explain the ternary conditional operator in
PHP?
Expression preceding the ? is evaluated, if it’s
true, then the expression preceding the : is executed, otherwise, the
expression following : is executed.
What’s the difference between include and
require?
It’s how they handle failures. If the file is not
found by require(), it will cause a fatal error and halt the execution of the
script. If the file is not found by include(), a warning will be issued, but
execution will continue.
How many ways can we get the value of current
session id?
session_id() returns the session id for the
current session.
How can we destroy the cookie?
Set the cookie in past.
How To Read the Entire File into a Single
String?
If you have a file, and you want to read the
entire file into a single string, you can use the file_get_contents() function.
It opens the specified file, reads all characters in the file, and returns them
in a single string. Here is a PHP script example on how to file_get_contents():
<?php
$file =
file_get_contents("/windows/system32/drivers/etc/services");
print("Size of the file:
".strlen($file)."\n");
?>
This script will print:
Size of the file: 7116
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