Basic knowledge of php: basic knowledge of functions_PHP tutorial

Functions are available in all languages, so here are just the key points:

1> Definition: PHP does not need to define the return value type.
2> Function names are not case-sensitive, but when calling a function, the same form as when it was defined is usually used.
3>All functions and classes in PHP have global scope and can be defined internally and called externally, and vice versa.
4>PHP does not support function overloading, and it is not possible to undefine or redefine declared functions.
5> Recursive functions can be called in PHP. But avoid recursive function/method calls beyond 100-200 levels, as the stack may be corrupted and the current script may terminate.
6>Parameters with default values ​​must be at the last few in the parameter list.
7>Variable function. Functions can be called by renaming the function.
For example:
function helloWorld($name='PHP')
{
echo "Hello World ".$name;
}
$func=helloWorld;
$ func();//Call helloWorld function
$func('Saga');//Call helloWorld with parameters
8> Variable length parameter list:
Mainly relies on three functions: func_num_args() , func_get_arg(), and func_get_args()
The description is as follows:
int func_num_args ( ) Returns the number of passed parameters. (PHP4, PHP5)
mixed func_get_arg ( int arg_num ) Returns the arg_numth parameter (from Counting starts at 0)
array func_get_args ( ) Returns the parameter expression group.

http://www.bkjia.com/PHPjc/317416.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/317416.htmlTechArticle functions are available in all languages, so here are just the key points: 1 Definition: PHP does not need to define a return value type . 2 Function names are not case-sensitive, but when calling a function, you usually use...