PHP (Hypertext Preprocessor) is a widely-used open source general-purpose scripting language that is especially suited for web development and can be embedded into HTML.
1. What is PHP stands for?
Hyper text Pre Processor
2. Who is the Father of PHP?
Rasmus Lerdorf
3. What is PHP?
PHP is a server side scripting language commonly used for web applications. PHP has many frameworks and cms for creating websites.
Even a non technical person can create sites using its CMS. WordPress, osCommerce are the famus CMS of php.
It is also an object oriented programming language like java,C-sharp etc.It is very eazy for learning
4. What is the use of “echo” in php?
It is used to print a data in the webpage, Example: <?php echo ‘Car insurance’; ?> , The following code print the text in the webpage
5. How to include a file to a php page?
We can include a file using “include() ” or “require()” function with file path as its parameter.
6. What’s the difference between include and require?
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.
7. What is the difference between Session and Cookie?
The main difference between sessions and cookies is that sessions are stored on the server, and cookies are stored on the user’s computers in the text file format. Cookies can not hold multiple variables,But Session can hold multiple variables.
We can set expiry for a cookie,The session only remains active as long as the browser isopen.Users do not have access to the data you stored in Session,Since it is stored in the server.Session is mainly used for login/logout purpose while cookies using for user activity tracking
8. require_once(), require(), include().What is difference between them?
require() includes and evaluates a specific file, while require_once() does that only if it has not been included before (on the same page).
So, require_once() is recommended to use when you want to include a file where you have a lot of functions for example. This way you make sure you don’t include the file more times and you will not get the “function re-declared” error.
9. Differences between GET and POST methods ?
We can send 1024 bytes using GET method but POST method can transfer large amount of data and POST is the secure method than GET method .
10. List out some tools through which we can draw E-R diagrams for mysql.
1. Case Studio
2. Smart Draw
11. How to declare an array in php?
Eg : var $arr = array(‘apple’, ‘grape’, ‘lemon’);
12. What is use of count() function in php ?
count() is used to count all elements in an array, or something in an object
13. How to set cookies in PHP?
Setcookie(“sample”, “ram”, time()+3600);
14. How to Retrieve a Cookie Value?
eg : echo $_COOKIE["user"];
15. How to create a session? How to set a value in session ? How to Remove data from a session?
Create session : session_start();
Set value into session : $_SESSION['USER_ID']=1;
Remove data from a session : unset($_SESSION['USER_ID'];
16. What types of loops exist in php?
for,while,do while and foreach (NB: You should learn its usage)
17. How do you connet mysql database with PHP ? How to create a mysql connection?
We can connect Mysql Database with PHP using both Procedural and Object oriented style like below
$link = mysqli_connect("localhost", "username", "password", "dbofpcds");
$mysqli = new mysqli("localhost", "username", "password", "dbname");
and in old type of connectivity were
$link = mysql_connect("localhost", "username", "password");
mysql_select_db("database",$link);
for connection use: mysql_connect(servername,username,password);
18. How can we create a database using PHP and MySQL? How to select a database?
We can create MySQL database with the use of mysql_create_db("Database Name")
We can select database suing function: mysql_select_db($db_name);
19. How to execute an sql query? How to fetch its result ?
$my_qry = mysql_query(“SELECT * FROM `users` WHERE `u_id`=’1′; “);
$result = mysql_fetch_array($my_qry);
echo $result['First_name'];
20. How we can retrieve the data in the result set of MySQL using PHP?
1. mysql_fetch_row
2. mysql_fetch_array
3. mysql_fetch_object
4. mysql_fetch_assoc
21. What is the use of explode() function ?
Syntax : array explode ( string $delimiter , string $string [, int $limit ] );
What is PHP?
- PHP is an acronym for "PHP Hypertext Preprocessor"
- PHP is a widely-used, open source scripting language
- PHP scripts are executed on the server
- PHP costs nothing, it is free to download and use
Top PHP Interview Questions with Answers for freshers and experienced are below are below :
1. What is PHP stands for?
Hyper text Pre Processor
2. Who is the Father of PHP?
Rasmus Lerdorf
3. What is PHP?
PHP is a server side scripting language commonly used for web applications. PHP has many frameworks and cms for creating websites.
Even a non technical person can create sites using its CMS. WordPress, osCommerce are the famus CMS of php.
It is also an object oriented programming language like java,C-sharp etc.It is very eazy for learning
4. What is the use of “echo” in php?
It is used to print a data in the webpage, Example: <?php echo ‘Car insurance’; ?> , The following code print the text in the webpage
5. How to include a file to a php page?
We can include a file using “include() ” or “require()” function with file path as its parameter.
6. What’s the difference between include and require?
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.
7. What is the difference between Session and Cookie?
The main difference between sessions and cookies is that sessions are stored on the server, and cookies are stored on the user’s computers in the text file format. Cookies can not hold multiple variables,But Session can hold multiple variables.
We can set expiry for a cookie,The session only remains active as long as the browser isopen.Users do not have access to the data you stored in Session,Since it is stored in the server.Session is mainly used for login/logout purpose while cookies using for user activity tracking
8. require_once(), require(), include().What is difference between them?
require() includes and evaluates a specific file, while require_once() does that only if it has not been included before (on the same page).
So, require_once() is recommended to use when you want to include a file where you have a lot of functions for example. This way you make sure you don’t include the file more times and you will not get the “function re-declared” error.
9. Differences between GET and POST methods ?
We can send 1024 bytes using GET method but POST method can transfer large amount of data and POST is the secure method than GET method .
10. List out some tools through which we can draw E-R diagrams for mysql.
1. Case Studio
2. Smart Draw
Also Read: Top 25 SEO Interview Questions and Answers
11. How to declare an array in php?
Eg : var $arr = array(‘apple’, ‘grape’, ‘lemon’);
12. What is use of count() function in php ?
count() is used to count all elements in an array, or something in an object
13. How to set cookies in PHP?
Setcookie(“sample”, “ram”, time()+3600);
14. How to Retrieve a Cookie Value?
eg : echo $_COOKIE["user"];
15. How to create a session? How to set a value in session ? How to Remove data from a session?
Create session : session_start();
Set value into session : $_SESSION['USER_ID']=1;
Remove data from a session : unset($_SESSION['USER_ID'];
16. What types of loops exist in php?
for,while,do while and foreach (NB: You should learn its usage)
17. How do you connet mysql database with PHP ? How to create a mysql connection?
We can connect Mysql Database with PHP using both Procedural and Object oriented style like below
$link = mysqli_connect("localhost", "username", "password", "dbofpcds");
$mysqli = new mysqli("localhost", "username", "password", "dbname");
and in old type of connectivity were
$link = mysql_connect("localhost", "username", "password");
mysql_select_db("database",$link);
for connection use: mysql_connect(servername,username,password);
18. How can we create a database using PHP and MySQL? How to select a database?
We can create MySQL database with the use of mysql_create_db("Database Name")
We can select database suing function: mysql_select_db($db_name);
19. How to execute an sql query? How to fetch its result ?
$my_qry = mysql_query(“SELECT * FROM `users` WHERE `u_id`=’1′; “);
$result = mysql_fetch_array($my_qry);
echo $result['First_name'];
20. How we can retrieve the data in the result set of MySQL using PHP?
1. mysql_fetch_row
2. mysql_fetch_array
3. mysql_fetch_object
4. mysql_fetch_assoc
Also Read: Top 20 JSP Interview Questions and Answers
21. What is the use of explode() function ?
Syntax : array explode ( string $delimiter , string $string [, int $limit ] );
This function breaks a string into an array. Each of the array elements is a substring of string formed by splitting it on boundaries formed by the string delimiter.
22. What is the difference between explode() and split() functions?
Split function splits string into array by regular expression. Explode splits a string into array by string.
23. Write down the code for save an uploaded file in php.
if ($_FILES["file"]["error"] == 0)
{
move_uploaded_file($_FILES["file"]["tmp_name"],
“upload/” . $_FILES["file"]["name"]);
echo “Stored in: ” . “upload/” . $_FILES["file"]["name"];
}
24. How to create a text file in php?
$filename = “/home/user/guest/newfile.txt”;
$file = fopen( $filename, “w” );
if( $file == false )
{
echo ( “Error in opening new file” ); exit();
}
fwrite( $file, “This is a simple test\n” );
fclose( $file );
25. How to strip whitespace (or other characters) from the beginning and end of a string ?
The trim() function removes whitespaces or other predefined characters from both sides of a string.
26. What is the use of header() function in php ?
The header() function sends a raw HTTP header to a client browser.Remember that this function must be called before sending the actual out put.For example, You do not print any HTML element before using this function.
27. How to redirect a page in php ?
The following code can be used for it, header(“Location:index.php”);
28. How stop the execution of a php scrip ?
exit() function is used to stop the execution of a page
29. How to set a page as a home page in a php based site ?
index.php is the default name of the home page in php based sites
30. What is the use of rand() in php?
It is used to generate random numbers. If called without the arguments it returns a pseudo-random integer between 0 and getrandmax().
If you want a random number between 6 and 12 (inclusive), for example, use rand(6, 12).This function does not generate cryptographically safe values, and should not be used for cryptographic uses.
If you want a cryptographically secure value, consider using openssl_random_pseudo_bytes() instead.
31. What is the use of isset() in php?
This function is used to determine if a variable is set and is not NULL
32. What is the difference between mysql_fetch_array() and mysql_fetch_assoc() ?
mysql_fetch_assoc function Fetch a result row as an associative array, While mysql_fetch_array() fetches an associative array, a numeric array, or both
33. What is mean by an associative array?
Associative arrays are arrays that use string keys is called associative arrays.
34. What is the importance of “method” attribute in a html form?
“method” attribute determines how to send the form-data into the server.There are two methods, get and post. The default method is get. This sends the form information by appending it on the URL.Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
35. What is the importance of “action” attribute in a html form?
The action attribute determines where to send the form-data in the form submission.
36. How to create an array of a group of items inside an HTML form ?
We can create input fields with same name for “name” attribute with squire bracket at the end of the name of the name attribute, It passes data as an array to PHP.
For instance :
<input name=”MyArray[]” /> <input name=”MyArray[]” /> <input name=”MyArray[]” /> <input name=”MyArray[]” />
37. Define Object-Oriented Methodology
Object orientation is a software/Web development methodology that is based on the modeling a real worldsystem.
An object is the core concept involved in the object orientation. An object is the copy of the real worldenity.An object oriented model is a collection of objects and its inter-relationships
38. How do you define a constant?
Using define() directive, like define (“MYCONSTANT”,150)
39. How send email using php?
To send email using PHP, you use the mail() function.This mail() function accepts 5 parameters as follows (the last 2 are optional).
You need webserver, you can’t send email from localhost.
eg : mail($to,$subject,$message,$headers);
40. How to find current date and time?
The date() function provides you with a means of retrieving the current date and time, applying the format integer parameters indicated in your script to the timestamp provided or the current local time if no timestamp is given. In simplified terms, passing a time parameter is optional – if you don’t, the current timestamp will be used.
41. Difference between mysql_connect and mysql_pconnect?
There is a good page in the php manual on the subject, in short mysql_pconnect() makes a persistent connection to the database which means a SQL link that do not close when the execution of your script ends.
mysql_connect()provides only for the databasenewconnection while using mysql_pconnect , the function would first try to find a (persistent) link that’s already open with the same host, username and password.
If one is found, an identifier for it will be returned instead of opening a new connection… the connection to the SQL server will not be closed when the execution of the script ends. Instead, the link will remain open for future use.
42. What is the difference between $var and $var?
They are both variables. But $var is a variable with a fixed name. $var is a variable who’s name is stored in $var. For example, if $var contains “message”, $var is the same as $message.
43. What are the encryption techniques in PHP?
MD5 PHP implements the MD5 hash algorithm using the md5 function,
eg : $encrypted_text = md5 ($msg);
mcrypt_encrypt :- string mcrypt_encrypt ( string $cipher , string $key , string $data , string $mode [, string $iv ] );
Encrypts plaintext with given parameters
44. How to delete a file from the system
Unlink() deletes the given file from the file system.
45. How to get the value of current session id?
22. What is the difference between explode() and split() functions?
Split function splits string into array by regular expression. Explode splits a string into array by string.
23. Write down the code for save an uploaded file in php.
if ($_FILES["file"]["error"] == 0)
{
move_uploaded_file($_FILES["file"]["tmp_name"],
“upload/” . $_FILES["file"]["name"]);
echo “Stored in: ” . “upload/” . $_FILES["file"]["name"];
}
24. How to create a text file in php?
$filename = “/home/user/guest/newfile.txt”;
$file = fopen( $filename, “w” );
if( $file == false )
{
echo ( “Error in opening new file” ); exit();
}
fwrite( $file, “This is a simple test\n” );
fclose( $file );
25. How to strip whitespace (or other characters) from the beginning and end of a string ?
The trim() function removes whitespaces or other predefined characters from both sides of a string.
Also Read: Top 25 QA Interview Questions and Answers
26. What is the use of header() function in php ?
The header() function sends a raw HTTP header to a client browser.Remember that this function must be called before sending the actual out put.For example, You do not print any HTML element before using this function.
27. How to redirect a page in php ?
The following code can be used for it, header(“Location:index.php”);
28. How stop the execution of a php scrip ?
exit() function is used to stop the execution of a page
29. How to set a page as a home page in a php based site ?
index.php is the default name of the home page in php based sites
30. What is the use of rand() in php?
It is used to generate random numbers. If called without the arguments it returns a pseudo-random integer between 0 and getrandmax().
If you want a random number between 6 and 12 (inclusive), for example, use rand(6, 12).This function does not generate cryptographically safe values, and should not be used for cryptographic uses.
If you want a cryptographically secure value, consider using openssl_random_pseudo_bytes() instead.
31. What is the use of isset() in php?
This function is used to determine if a variable is set and is not NULL
32. What is the difference between mysql_fetch_array() and mysql_fetch_assoc() ?
mysql_fetch_assoc function Fetch a result row as an associative array, While mysql_fetch_array() fetches an associative array, a numeric array, or both
33. What is mean by an associative array?
Associative arrays are arrays that use string keys is called associative arrays.
34. What is the importance of “method” attribute in a html form?
“method” attribute determines how to send the form-data into the server.There are two methods, get and post. The default method is get. This sends the form information by appending it on the URL.Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
35. What is the importance of “action” attribute in a html form?
The action attribute determines where to send the form-data in the form submission.
Also Read: Top 25 CSS Interview Questions with Answers
36. How to create an array of a group of items inside an HTML form ?
We can create input fields with same name for “name” attribute with squire bracket at the end of the name of the name attribute, It passes data as an array to PHP.
For instance :
<input name=”MyArray[]” /> <input name=”MyArray[]” /> <input name=”MyArray[]” /> <input name=”MyArray[]” />
37. Define Object-Oriented Methodology
Object orientation is a software/Web development methodology that is based on the modeling a real worldsystem.
An object is the core concept involved in the object orientation. An object is the copy of the real worldenity.An object oriented model is a collection of objects and its inter-relationships
38. How do you define a constant?
Using define() directive, like define (“MYCONSTANT”,150)
39. How send email using php?
To send email using PHP, you use the mail() function.This mail() function accepts 5 parameters as follows (the last 2 are optional).
You need webserver, you can’t send email from localhost.
eg : mail($to,$subject,$message,$headers);
40. How to find current date and time?
The date() function provides you with a means of retrieving the current date and time, applying the format integer parameters indicated in your script to the timestamp provided or the current local time if no timestamp is given. In simplified terms, passing a time parameter is optional – if you don’t, the current timestamp will be used.
41. Difference between mysql_connect and mysql_pconnect?
There is a good page in the php manual on the subject, in short mysql_pconnect() makes a persistent connection to the database which means a SQL link that do not close when the execution of your script ends.
mysql_connect()provides only for the databasenewconnection while using mysql_pconnect , the function would first try to find a (persistent) link that’s already open with the same host, username and password.
If one is found, an identifier for it will be returned instead of opening a new connection… the connection to the SQL server will not be closed when the execution of the script ends. Instead, the link will remain open for future use.
42. What is the difference between $var and $var?
They are both variables. But $var is a variable with a fixed name. $var is a variable who’s name is stored in $var. For example, if $var contains “message”, $var is the same as $message.
43. What are the encryption techniques in PHP?
MD5 PHP implements the MD5 hash algorithm using the md5 function,
eg : $encrypted_text = md5 ($msg);
mcrypt_encrypt :- string mcrypt_encrypt ( string $cipher , string $key , string $data , string $mode [, string $iv ] );
Encrypts plaintext with given parameters
44. How to delete a file from the system
Unlink() deletes the given file from the file system.
45. How to get the value of current session id?
session_id() function returns the session id for the current session.
46. 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, a numeric array, or both.
mysql_fetch_object ( resource result ) 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.
47. What is sql injection ?
SQL injection is a malicious code injection technique.It exploiting SQL vulnerabilities in Web applications
48. What is x+ mode in fopen() used for?
Read/Write. Creates a new file. Returns FALSE and an error if file already exists
49. What is PEAR?
PEAR is a framework and distribution system for reusable PHP components.The project seeks to provide a structured library of code, maintain a system for distributing code and for managing code packages, and promote a standard coding style.
PEAR is broken into three classes: PEAR Core Components, PEAR Packages, and PECL Packages.
The Core Components include the base classes of PEAR and PEAR_Error, along with database, HTTP, logging, and e-mailing functions. The PEAR Packages include functionality providing for authentication, networking, and file system features, as well as tools for working with XML and HTML templates.
50. Distinguish between urlencode and urldecode?
This method is best when encode a string to used in a query part of a url. it returns a string in which all non-alphanumeric characters except -_. have replece with a percentege(%) sign . the urldecode->Decodes url to encode string as any %and other symbole are decode by the use of the urldecode() function.
51. What are the different errors in PHP?
In PHP, there are three types of runtime errors, they are:
1. Notices: These errors are non-critical and trivial errors that come across while executing the script in PHP. Example: trying to gain access the variable which is not defined. These errors are not showed to the users by default even if the default behavior is changed.
2. Warnings: These are important errors. Example: When we try to include () file which is not available. These errors are showed to the user by default but they will not result in ending the script.
3. Fatal errors: These are critical errors. Example: instantiating an object of a class which does not exist or a non-existent function is called. These errors results in termination of the script immediately and default behavior of PHP is shown to them when they take place. Twelve different error types are used to represent these variations internally.
Also Read: Best PHP Frameworks for Developer in 2015
46. 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, a numeric array, or both.
mysql_fetch_object ( resource result ) 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.
47. What is sql injection ?
SQL injection is a malicious code injection technique.It exploiting SQL vulnerabilities in Web applications
48. What is x+ mode in fopen() used for?
Read/Write. Creates a new file. Returns FALSE and an error if file already exists
49. What is PEAR?
PEAR is a framework and distribution system for reusable PHP components.The project seeks to provide a structured library of code, maintain a system for distributing code and for managing code packages, and promote a standard coding style.
PEAR is broken into three classes: PEAR Core Components, PEAR Packages, and PECL Packages.
The Core Components include the base classes of PEAR and PEAR_Error, along with database, HTTP, logging, and e-mailing functions. The PEAR Packages include functionality providing for authentication, networking, and file system features, as well as tools for working with XML and HTML templates.
50. Distinguish between urlencode and urldecode?
This method is best when encode a string to used in a query part of a url. it returns a string in which all non-alphanumeric characters except -_. have replece with a percentege(%) sign . the urldecode->Decodes url to encode string as any %and other symbole are decode by the use of the urldecode() function.
51. What are the different errors in PHP?
In PHP, there are three types of runtime errors, they are:
1. Notices: These errors are non-critical and trivial errors that come across while executing the script in PHP. Example: trying to gain access the variable which is not defined. These errors are not showed to the users by default even if the default behavior is changed.
2. Warnings: These are important errors. Example: When we try to include () file which is not available. These errors are showed to the user by default but they will not result in ending the script.
3. Fatal errors: These are critical errors. Example: instantiating an object of a class which does not exist or a non-existent function is called. These errors results in termination of the script immediately and default behavior of PHP is shown to them when they take place. Twelve different error types are used to represent these variations internally.
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