Amadeus IT Group Most Frequently Asked Latest PHP Interview Questions Answers
How To Close A Session Properly?
Let's say you site requires users to login. When a logged in user clicks the logout button, you need to close the session associated with this user properly in 3 steps:
1. Remove all session values with $_SESSION = array().
2. Remove the session ID cookie with the setcookie() function.
3. Destroy the session object with the session_destroy() function.
Below is a good sample script:
<?php
session_start();
$_SESSION = array();
if (isset($_COOKIE[session_name()])) {
setcookie(session_name(), '', time()-42000, '/');
}
session_destroy();
print("<html><pre>");
print("Thank you for visiting PICKZYCenter.com.\n");
print(" <a href=login.php>Login Again.</a>\n");
print("</pre></html>\n");
?>
Just use the PHP command line interface (CLI) and specify the file name of the script to be executed as follows:
php script.php
How can PHP and HTML interact?
It is possible to generate HTML through PHP scripts, and it is possible to pass pieces of information from HTML to PHP.
What type of operation is needed when passing values through a form or an URL?
If we would like to pass values through a form or an URL, then we need to encode and to decode them using htmlspecialchars() and urlencode().
How can we check the value of a given variable is a number?
It is possible to use the dedicated function, is_numeric() to check whether it is a number or not.
How can we check the value of a given variable is alphanumeric?
It is possible to use the dedicated function, ctype_alnum to check whether it is an alphanumeric value or not.
How do I check if a given variable is empty?
If we want to check whether a variable has a value or not, it is possible to use the empty() function.
What are the functions to be used to get the image's properties (size, width, and height)?
The functions are getimagesize() for size, imagesx() for width and imagesy() for height.
How failures in execution are handled with include() and require() functions?
If the function require() cannot access the file then it ends with a fatal error. However, the include() function gives a warning, and the PHP script continues to execute.
What is the main difference between require() and require_once()?
require(), and require_once() perform the same task except that the second function checks if the PHP script is already included or not before executing it.
(same for include_once() and include())
How can I display text with a PHP script?
Two methods are possible:
<!--?php echo "Method 1"; print "Method 2"; ?-->
How can we display information of a variable and readable by a human with PHP?
To be able to display a human-readable result we use print_r().
How is it possible to set an infinite execution time for PHP script?
The set_time_limit(0) added at the beginning of a script sets to infinite the time of execution to not have the PHP error 'maximum execution time exceeded.' It is also possible to specify this in the php.ini file.
What does the PHP error 'Parse error in PHP - unexpected T_variable at line x' means?
This is a PHP syntax error expressing that a mistake at the line x stops parsing and executing the program.
What should we do to be able to export data into an Excel file?
The most common and used way is to get data into a format supported by Excel. For example, it is possible to write a .csv file, to choose for example comma as a separator between fields and then to open the file with Excel.
What is the function file_get_contents() useful for?
file_get_contents() lets reading a file and storing it in a string variable.
How can we connect to a MySQL database from a PHP script?
To be able to connect to a MySQL database, we must use mysqli_connect() function as follows:
<!--?php $database = mysqli_connect("HOST", "USER_NAME", "PASSWORD"); mysqli_select_db($database,"DATABASE_NAME"); ?-->
What is the function mysql_pconnect() useful for?
mysql_pconnect() ensure a persistent connection to the database, it means that the connection does not close when the PHP script ends.
This function is not supported in PHP 7.0 and above
How be the result set of Mysql handled in PHP?
The result set can be handled using mysqli_fetch_array, mysqli_fetch_assoc, mysqli_fetch_object or mysqli_fetch_row.
How is it possible to know the number of rows returned in the result set?
The function mysqli_num_rows() returns the number of rows in a result set.
The unlink() function is dedicated for file system handling. It simply deletes the file given as entry.
What does the unset() function mean?
The unset() function is dedicated for variable management. It will make a variable undefined.
How do I escape data before storing it in the database?
The addslashes function enables us to escape data before storage into the database.
How is it possible to remove escape characters from a string?
The stripslashes function enables us to remove the escape characters before apostrophes in a string.
How can we automatically escape incoming data?
We have to enable the Magic quotes entry in the configuration file of PHP.
What does the function get_magic_quotes_gpc() means?
The function get_magic_quotes_gpc() tells us whether the magic quotes is switched on or no.
Is it possible to remove the HTML tags from data?
The strip_tags() function enables us to clean a string from the HTML tags.
what is the static variable in function useful for?
A static variable is defined within a function only the first time, and its value can be modified during function calls as follows:
<!--?php function testFunction() { static $testVariable = 1; echo $testVariable; $testVariable++; } testFunction(); //1 testFunction(); //2 testFunction(); //3 ?-->
How is it possible to cast types in PHP?
The name of the output type has to be specified in parentheses before the variable which is to be cast as follows:
* (int), (integer) - cast to integer
* (bool), (boolean) - cast to boolean
* (float), (double), (real) - cast to float
* (string) - cast to string
* (array) - cast to array
* (object) - cast to object.
How To Close A Session Properly?
Let's say you site requires users to login. When a logged in user clicks the logout button, you need to close the session associated with this user properly in 3 steps:
1. Remove all session values with $_SESSION = array().
2. Remove the session ID cookie with the setcookie() function.
3. Destroy the session object with the session_destroy() function.
Below is a good sample script:
<?php
session_start();
$_SESSION = array();
if (isset($_COOKIE[session_name()])) {
setcookie(session_name(), '', time()-42000, '/');
}
session_destroy();
print("<html><pre>");
print("Thank you for visiting PICKZYCenter.com.\n");
print(" <a href=login.php>Login Again.</a>\n");
print("</pre></html>\n");
?>
How do you execute a PHP script from the command line?
Just use the PHP command line interface (CLI) and specify the file name of the script to be executed as follows:
php script.php
How can PHP and HTML interact?
It is possible to generate HTML through PHP scripts, and it is possible to pass pieces of information from HTML to PHP.
What type of operation is needed when passing values through a form or an URL?
If we would like to pass values through a form or an URL, then we need to encode and to decode them using htmlspecialchars() and urlencode().
How can we check the value of a given variable is a number?
It is possible to use the dedicated function, is_numeric() to check whether it is a number or not.
How can we check the value of a given variable is alphanumeric?
It is possible to use the dedicated function, ctype_alnum to check whether it is an alphanumeric value or not.
How do I check if a given variable is empty?
If we want to check whether a variable has a value or not, it is possible to use the empty() function.
What are the functions to be used to get the image's properties (size, width, and height)?
The functions are getimagesize() for size, imagesx() for width and imagesy() for height.
How failures in execution are handled with include() and require() functions?
If the function require() cannot access the file then it ends with a fatal error. However, the include() function gives a warning, and the PHP script continues to execute.
What is the main difference between require() and require_once()?
require(), and require_once() perform the same task except that the second function checks if the PHP script is already included or not before executing it.
(same for include_once() and include())
How can I display text with a PHP script?
Two methods are possible:
<!--?php echo "Method 1"; print "Method 2"; ?-->
 |
| Amadeus IT Group Most Frequently Asked Latest PHP Interview Questions Answers |
How can we display information of a variable and readable by a human with PHP?
To be able to display a human-readable result we use print_r().
How is it possible to set an infinite execution time for PHP script?
The set_time_limit(0) added at the beginning of a script sets to infinite the time of execution to not have the PHP error 'maximum execution time exceeded.' It is also possible to specify this in the php.ini file.
What does the PHP error 'Parse error in PHP - unexpected T_variable at line x' means?
This is a PHP syntax error expressing that a mistake at the line x stops parsing and executing the program.
What should we do to be able to export data into an Excel file?
The most common and used way is to get data into a format supported by Excel. For example, it is possible to write a .csv file, to choose for example comma as a separator between fields and then to open the file with Excel.
What is the function file_get_contents() useful for?
file_get_contents() lets reading a file and storing it in a string variable.
How can we connect to a MySQL database from a PHP script?
To be able to connect to a MySQL database, we must use mysqli_connect() function as follows:
<!--?php $database = mysqli_connect("HOST", "USER_NAME", "PASSWORD"); mysqli_select_db($database,"DATABASE_NAME"); ?-->
What is the function mysql_pconnect() useful for?
mysql_pconnect() ensure a persistent connection to the database, it means that the connection does not close when the PHP script ends.
This function is not supported in PHP 7.0 and above
How be the result set of Mysql handled in PHP?
The result set can be handled using mysqli_fetch_array, mysqli_fetch_assoc, mysqli_fetch_object or mysqli_fetch_row.
How is it possible to know the number of rows returned in the result set?
The function mysqli_num_rows() returns the number of rows in a result set.
What does the unlink() function mean?
The unlink() function is dedicated for file system handling. It simply deletes the file given as entry.
What does the unset() function mean?
The unset() function is dedicated for variable management. It will make a variable undefined.
How do I escape data before storing it in the database?
The addslashes function enables us to escape data before storage into the database.
How is it possible to remove escape characters from a string?
The stripslashes function enables us to remove the escape characters before apostrophes in a string.
How can we automatically escape incoming data?
We have to enable the Magic quotes entry in the configuration file of PHP.
What does the function get_magic_quotes_gpc() means?
The function get_magic_quotes_gpc() tells us whether the magic quotes is switched on or no.
Is it possible to remove the HTML tags from data?
The strip_tags() function enables us to clean a string from the HTML tags.
what is the static variable in function useful for?
A static variable is defined within a function only the first time, and its value can be modified during function calls as follows:
<!--?php function testFunction() { static $testVariable = 1; echo $testVariable; $testVariable++; } testFunction(); //1 testFunction(); //2 testFunction(); //3 ?-->
How is it possible to cast types in PHP?
The name of the output type has to be specified in parentheses before the variable which is to be cast as follows:
* (int), (integer) - cast to integer
* (bool), (boolean) - cast to boolean
* (float), (double), (real) - cast to float
* (string) - cast to string
* (array) - cast to array
* (object) - cast to object.
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