What is a variable number of parameters for PHP functions

PHP supports a variable number of parameter lists in user-defined functions.

In php5.5 and earlier versions, the Func_num_args (), Func_get_arg (), and Func_get_args () functions were implemented.

<?phpfunction MyFunc () {    //Get the number of parameters    echo Func_num_args (). Php_eol;    Gets the value of the first parameter:    print_r (func_get_arg (0));    echo Php_eol;    Gets the value of all parameters    Print_r (Func_get_args ());    echo Php_eol;} MyFunc (' a '); MyFunc (1, 2, 3); MyFunc (Array (' d ', ' e '), array (' F '));? >

Output:

1aArray (    [0] = a) 31Array (    [0] = 1    [1] = 2    [2] + 3) 2Array (    [0] = + d    [1] = > E) Array (    [0] = = Array        (            [0] = + d            [1] = + e        )    [1] = = Array        (            [0] + F        ))

In versions php5.6 and above, you can use ... Syntax implementation.

Example 1: Using the ... $args instead of any number of parameters

<?phpfunction myfunc (... $args) {    //Get the number of parameters    echo count ($args). Php_eol;    Gets the value of the first parameter:    print_r ($args [0]);    echo Php_eol;    Gets the value of all parameters    Print_r ($args);    echo Php_eol;} MyFunc (' a '); MyFunc (1, 2, 3); MyFunc (Array (' d ', ' e '), array (' F '));? >

The output is consistent with php5.5 using Func_num_args (), Func_get_arg (), and the Func_get_args () function.

Example 2: Array to parameter list

<?phpfunction Add ($a, $b) {    echo $a + $b;} $args = Array (1, 2); Add (... $args); Output 3?>

Example 3: Partial parameter designation, variable number of other parameters

<?phpfunction display ($name, $tag, ... $args) {    echo ' name: '. $name. Php_eol;        Echo ' tag: '. $tag. Php_eol;        echo ' args: '. Php_eol;    Print_r ($args);        echo Php_eol;} Display (' Fdipzone ', ' Programmer ');d isplay (' Terry ', ' Designer ', 1, 2);d isplay (' Aoao ', ' tester ', Array (' A ', ' B '), Array ( ' C '), Array (' d '));? >

Output:

Name:fdipzonetag:programmerargs:Array () name:terrytag:designerargs:Array (    [0] = 1    [1] = 2) Name: Aoaotag:testerargs:Array (    [0] = = Array        (            [0] = a            [1] = b        )    [1] = = Array        (            [0] = c        )    [2] = = Array        (            [0] = d        ))