Build-IN Functions

• What is a function?
• A function is a block of code that can reusable.

• What is a build-in function?
• PHP provides many functions that you can use to work with data. The functions are refered to as build-in functions.

• Some of basic build-in function:
• number-format($number[,$decimal]): this function return number that is formatted with a comma(,)
• Exmple:$nf=number-format(12345)      //12.345
• Example:$nf=number-format(12345,2) //12,345
• date($format): this function return current date with specificed format string.
• Example: $date=date('Y-m-d')   // 2014/13/11
• Three functions for checking variable values.
• isset($var): return true if the variable have been set and is not null value.
• empty($var): return true if the variable hasn't been set ,contain null value or contain an empty string.

• Build-in functions that you can use to pass control to another page.
• As a PHP application executes, it moves from one web page to another. To do that, you can use the include and require function.
• include($path):Insert and run the specified file. If function fail ,it cause a warning,that allow script to continue.
• include_once($path): Same as the include function. But it make sure that the file include only once.
• require($path): Works the same include function. However, if function fails it causes a fatal error that stop script.
• require_once($path): Same as require function. But it make sure that the file include only once.
• exit($status): Exits the current PHP script.