Question 1

What is difference between MyISAM and InnoDB storage engines in mysql.

Accepted Answer

1 : InnoDB provides us row level locking while MyISAM provides us table level locking 2 : InnoDB offers foreign key constraints wheres in MyISAM does not have foreign key constraints 3 : InnoDB does not have full text search wheres MyISAM provides us full text search

Question 2

What is the use of header() function in php?

Accepted Answer

The header() function sends a raw HTTP header to a client We can use header() function for redirection of pages It is important to notice that header() must be called before any actual output is seen

Question 3

How we get IP address of client,previous reference page etc?

Accepted Answer

By using $_SERVER['REMOTE_ADDR'], $_['HTTP_REFERER'] etc

Question 4

What is the difference between the functions unlink and unset?

Accepted Answer

unlink()-deletes the given file from the file system unset() -makes a variable undefined

Question 5

What are the different functions in sorting an array?

Accepted Answer

sort() , rsort(), asort() ksort() , usort() arsort() , uksort() natsort() , natcasesort() array_multisort()

Question 6

How many types of Inheritances used in php and how we achieve it?

Accepted Answer

As far PHP concern it only support single Inheritance in scripting we can also use interface to achieve multiple inheritance

Question 7

What is PHP's mysqli Extension?

Accepted Answer

The mysqli extension , or as it is sometimes known, the MYSQL improved extension ,was developed to take advantage of new features found in MYSQL systems versions 413 and later The mysqli extension has a number of benfits,the key enhancements over the mysql extension being: => Object-oriented interface => Support for prepared statements => Support for multiple statements => Support for transactions => Enhanced debugging capabilities => Embedded server support

Question 8

What is PHP?

Accepted Answer

PHP: Hypertext Preprocessor is open source server-side scripting language that is widely used for web development PHP scripts are executed on the server PHP allows writing dynamically generated web pages efficiently and quickly The syntax is mostly borrowed from C, Java and perl PHP is free to download and use

Question 9

What is PEAR in php?

Accepted Answer

PEAR(PHP Extension and Application Repository) is a framework and repository for reusable PHP components PEAR is a code repository containing all kinds of php code snippets and libraries PEAR also offers a command-line interface that can be used to automatically install "packages"

Question 10

Echo vs print statement

Accepted Answer

echo() and print() are language constructs in PHP, both are used to output strings The speed of both statements is almost the same echo() can take multiple expressions whereas print cannot take multiple expressions Print return true or false based on success or failure whereas echo doesn't return true or false

Question 11

$message vs $$message in PHP?

Accepted Answer

$message is a variable with a fixed name $$message is a variable whose name is stored in $message If $message contains "var", $$message is the same as $var

Question 12

Explain the different types of errors in PHP.

Accepted Answer

Notices, Warnings and Fatal errors are the types of errors in PHP Notices: Notices represents non-critical errors, ie accessing a variable that has not yet been defined By default, such errors are not displayed to the user at all but whenever required, you can change this default behavior Warnings: Warnings are more serious errors but they do not result in script termination ie calling include() a file which does not exist By default, these errors are displayed to the user Fatal errors: Fatal errors are critical errors ie calling a non-existent function or class These errors cause the immediate termination of the script

Question 13

What is MIME?

Accepted Answer

MIME - Multi-purpose Internet Mail Extensions MIME types represents a standard way of classifying file types over Internet Web servers and browsers have a list of MIME types, which facilitates files transfer of the same type in the same way, irrespective of operating system they are working in A MIME type has two parts: a type and a subtype They are separated by a slash (/) MIME type for Microsoft Word files is application and the subtype is msword, ie application/msword

Question 14

Why many companies are switching their current business language to PHP? Where PHP basically used?

Accepted Answer

PHP is rapidly gaining the popularity and many companies are switching their current language for this language PHP is a server side scripting language PHP executes the instructions on the server itself Server is a computer where the web site is located PHP is used to create dynamic pages and provides faster execution of the instructions

Question 15

What is the difference between PHP and JavaScript?

Accepted Answer

The difference lies with the execution of the languages PHP is server side scripting language, which means that it can’t interact directly with the user Whereas, JavaScript is client side scripting language, that is used to interact directly with the user

Question 16

How can we increase the execution time of a php script?

Accepted Answer

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 phpini 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

Question 17

What is the use of super-global arrays in PHP?

Accepted Answer

Super global arrays are the built in arrays that can be used anywhere They are also called as auto-global as they can be used inside a function as well The arrays with the longs names such as $HTTP_SERVER_VARS, must be made global before they can be used in an array This $HTTP_SERVER_VARS check your phpini setting for long arrays

Question 18

What is the use of $_Server and $_Env?

Accepted Answer

$_SERVER and $_ENV arrays contain different information The information depends on the server and operating system being used Most of the information can be seen of an array for a particular server and operating system The syntax is as follows: foreach($_SERVER as $key =>$value) { echo “Key=$key, Value=$value
”; }

Question 19

What is the difference between $argv and $argc? Give example?

Accepted Answer

To pass the information into the script from outside, help can be taken from the PHP CLI (Command line interface) method Suppose addition of two numbers has to be passed to PHP then it can be passed like this on the command line: php addphp 2 3 Here the script name is addphp, and 2 and 3 are the numbers that has to be added by the script These numbers are available inside the script in an array called $argv This array contains all the information on the command line; the statement is stored as follows: $argv[0]=addphp $argv[1]=2 $argv[2]=3 So, $argv always contains at least one element — the script name Then, in your script, you can use the following statements: $sum = $argv[1] + $argv[2]; echo $sum; $argc is a variable that stores the numbers of elements in $argv $argc is equal to at least 1, which is saved for the name of the script Example is $argc=3 using the above statements

Question 20

Explain how to work with Permissions in PHP.

Accepted Answer

Permissions in PHP are very similar to UNIX Each file has three types of permissions – Read, write and execute Permissions can be changed using the change mode or CHMOD command CHMOD is followed by 3 digit number specifying the permission type CHMOD 777 is for Read, Write and execute Unnecessary permissions can be stripped off using UNMASK command Unmask (777);

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