Most frequently Asked PHP Interview Questions and Answers for freshers and experienced pdf free download
1. 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.
2. 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.
3. What is meant by PEAR in php?
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"
3. 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";
4. 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.
5. What is the difference between $message and $$message?
$message is a simple variable whereas $$message is a reference variable. Example:
$user = 'bob'
is equivalent to
$holder = 'user';
$$holder = 'bob';
6. 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.
7. What does a special set of tags do in PHP?
What does a special set of tags <?= and ?> do in PHP?
The output is displayed directly to the browser.
8. How do you define a constant?
Via define() directive, like define ("MYCONSTANT", 100);
9. 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.
10. What is meant by urlencode and urldecode?
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.
11. 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.
12. 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.
13. 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.
14. Are objects passed by value or by reference?
Everything is passed by value.
15. 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.
16. How do you call a constructor for a parent class?
parent::constructor($value)
17. 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 nonexistent 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
18. 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>
19. How can we register the variables into a session?
session_register($session_var);
$_SESSION['var'] = 'value';
20. 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()">
More PHP Interview Questions & Answers: Click Here
More PHP Multiple Choice Questions: Click Here
1. 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.
2. 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.
3. What is meant by PEAR in php?
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"
3. 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";
4. 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.
5. What is the difference between $message and $$message?
$message is a simple variable whereas $$message is a reference variable. Example:
$user = 'bob'
is equivalent to
$holder = 'user';
$$holder = 'bob';
6. 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.
7. What does a special set of tags do in PHP?
What does a special set of tags <?= and ?> do in PHP?
The output is displayed directly to the browser.
8. How do you define a constant?
Via define() directive, like define ("MYCONSTANT", 100);
9. 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.
10. What is meant by urlencode and urldecode?
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.
11. 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.
12. 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.
13. 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.
14. Are objects passed by value or by reference?
Everything is passed by value.
15. 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.
16. How do you call a constructor for a parent class?
parent::constructor($value)
17. WHAT ARE THE DIFFERENT TYPES OF ERRORS IN PHP?
Here are three basic types of runtime errors in PHP:
1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script - for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all - although you can change this default behavior.
2. Warnings: These are more serious errors - for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.
3. Fatal errors: These are critical errors - for example, instantiating an object of a nonexistent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP's default behavior is to display them to the user when they take place.
Internally, these variations are represented by twelve different error types
18. How can we submit a form without a submit button?
If you don't want to use the Submit button to submit a form, you can use normal hyper links to submit a form. But you need to use some JavaScript code in the URL of the link.
For example:
<a href="javascript: document.myform.submit();">Submit Me</a>
19. How can we register the variables into a session?
session_register($session_var);
$_SESSION['var'] = 'value';
20. 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()">
More PHP Interview Questions & Answers: Click Here
More PHP Multiple Choice Questions: Click Here
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