$_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.
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What is the use of super-global arrays in PHP?
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 php.ini setting for long arrays.
What are the different components used in PHP for formatting?
The components that are used in PHP for formatting are as follows:
1. %: it tells the start of the formatting instruction.
2. Padding character (pad): is used to fill out the string when the value to be formatted is smaller than the width assigned. Pad can be a space, a 0, or any character preceded by a single quote (‘).
3. -: A symbol meaning to left-justify the characters. If this is not included, the characters are right-justified.
4. width: The number of characters to use for the value. If the value doesn’t fill the width, the padding character is used to pad the value. For example, if the width is 5, the padding character is 0, and the value is 1, the output is 00001.
5. dec: The number of decimal places to use for a number. This value is preceded by a decimal point.
6. type: The type of value. Use s(string) for string, f (float) for numbers that you want to format with decimal places.
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.
What are the different types of statements that are present in PHP?
There are four kinds of PHP statements that are present. They are as follows:
• Simple statement- these are the echo statements and end with a semicolon (;). PHP ignores white spaces between simple statements. Until it finds a semicolon it reads the statement.
• Complex/Conditional statements: these are the statements which deal with certain conditions that have to be executed to meet certain specific requirements. These are if and else block or switch statements. PHP reads the complete statement and doesn’t stop at the first semicolon it encounters. It looks for starting and ending braces to end the execution.
• Looping statements: statements that are repeated in a block. The feature that enables you to execute the statements repeatedly is called as loop. For example: for loop, while loop, do..while loop.
What is difference between require_once(), require(), include()?
require() includes and evaluates a specific file, if the file is not found then it shows a Fatal Error.
require_once() includes only the file which is not being included before. It is used to be recommended for the files where you have lots of functions stored.
include() includes the file, even if the file is not found, but it gives a warning to the user to include().
Why PHP is sometimes called as embedded scripting language?
PHP is a high level language which is used to allow users to write and understand it in human readable form and also use an interpreter to interpret the code which user write for the computer. PHP is used as an embedded scripting language for the web. PHP is embedded in HTML code. HTML tags are used to enclose the PHP language. HTML is used and PHP is code written in it in the same way as you write JavaScript in HTML.
What does ODBC do in context with PHP?
PHP supports many databases like dBase, Microsft SQL Server, Oracle, etc. But, it also supports databases like filePro, FrontBase and InterBase with ODBC connectivity. ODBC stands for Open Database connectivity, which is a standard that allows user to communicate with other databases like Access and IBM DB2.
What are the different types of Errors in PHP?
There are three basic types of runtime errors in PHP:
1. Notices: These are small, 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 the default behavior can be changed.
2. Warnings: Warnings are more severe errors like 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.
What is MIME?
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, i.e. application/msword.