PHP functions func_get_args(), func_get_arg() and func_num_args()_PHP tutorial

This article will summarize and compare the usage and differences of the three functions func_get_args(), func_get_arg() and func_num_args() in PHP. Please refer to them for reference. ​

I used these built-in functions today, record them for review
func_num_args() Returns the number of parameters passed in to the calling function, the type is integer

func_get_arg() Returns the specified parameter value

func_get_args() Returns the value of all parameters, the type is array

func_get_args
Returns an array containing the function parameter list

Description

array func_get_args( void )
This function returns an array, and each element of the array is equivalent to each parameter of the current user-defined function. func_get_args() will generate a warning if this function is called from outside the function definition.

func_get_arg
Return the specified parameters from the function parameter list

Description

mixed func_get_arg( int arg_num )
Returns the arg_numth parameter of the parameter list that defines the function, with parameters starting from 0. And calling this function outside the function definition will generate a warning; and when arg_num is greater than the number of parameters actually passed by the function, a warning will also be generated and FALSE will be returned.

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func_num_args
Returns the number of arguments passed to the function

Description

int func_num_args( void )
This function returns the number of arguments passed to the currently defined function. func_num_args() will generate a warning if this function is called from outside the function definition.

func_num_args() can be used in combination with func_get_arg() and func_get_args() to allow user-defined functions to accept variable-length parameter lists. When we build a PHP class, flexibly using these three functions can achieve very ideal results. For example, when creating a class that links PHP and MYSQL, you can write the following code:

The code is as follows

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class mydb{

代码如下	复制代码
class mydb{ private $user; private $pass; private $host; private $db; public function __construct(){ $num_args=func_num_args(); if($num_args>0){ $args=func_get_args(); $this->host=$args[0]; $this->user=$args[1]; $this->pass=$args[2]; this->connect(); } } …….. ?>

private $user;

private $pass;

private $host;

代码如下	复制代码
function foo() {     $numargs = func_num_args();     echo "Number of arguments: $numargs n";     if ($numargs >= 2) {         echo "Second argument is: " . func_get_arg(1) . " n";     }     $arg_list = func_get_args();     for ($i = 0; $i < $numargs; $i++) { echo "Argument $i is: " . $arg_list[$i] . " n"; } } foo(1, 2, 3); ?>

private $db;

public function __construct(){
$num_args=func_num_args();
if($num_args>0){
$args=func_get_args();
$this->host=$args[0];
$this->user=$args[1];

$this->pass=$args[2];
this->connect(); }

}

…….. ?>

Here is an example from the manual:

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function foo() { $numargs = func_num_args(); echo "Number of arguments: $numargs n"; If ($numargs >= 2) { echo "Second argument is: " . func_get_arg(1) . " n"; } $arg_list = func_get_args(); for ($i = 0; $i < $numargs; $i++) { echo "Argument $i is: " . $arg_list[$i] . " n"; }<🎜> }<🎜> <🎜>foo(1, 2, 3);<🎜> ?>

The output result is: Number of arguments: 3 Second argument is: 2 Argument 0 is: 1 Argument 1 is: 2 Argument 2 is: 3 http://www.bkjia.com/PHPjc/445610.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/445610.htmlTechArticleThis article will summarize the three functions of func_get_args(), func_get_arg() and func_num_args() in php Please refer to the usage and difference comparison of functions. I used this today...