PHP - Manual: func_num_args

2024-11-14

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func_num_args

(PHP 4, PHP 5, PHP 7, PHP 8)

func_num_args — Returns the number of arguments passed to the function

说明

func_num_args(): int

Gets the number of arguments passed to the function.

This function may be used in conjunction with func_get_arg() and func_get_args() to allow user-defined functions to accept variable-length argument lists.

返回值

Returns the number of arguments passed into the current user-defined function.

更新日志

版本	说明
5.3.0	This function can now be used in parameter lists.
5.3.0	If this function is called from the outermost scope of a file which has been included by calling include or require from within a function in the calling file, it now generates a warning and returns -1.

错误／异常

Generates a warning if called from outside of a user-defined function.

范例

示例 #1 func_num_args() example


<?php
function foo()
{
    $numargs = func_num_args();
    echo "Number of arguments: $numargs\n";
}

foo(1, 2, 3);   
?>

以上例程会输出：

Number of arguments: 3

示例 #2 func_num_args() example before and after PHP 5.3


test.php
<?php
function foo() {
    include './fna.php';
}

foo('First arg', 'Second arg');
?>

fna.php
<?php

$num_args = func_num_args();
var_export($num_args);

?>

Output previous to PHP 5.3:

Output in PHP 5.3 and later will be something similar to:

Warning: func_num_args():  Called from the global scope - no function
context in /home/torben/Desktop/code/ml/fna.php on line 3
-1

注释

注意:
因为函数依赖于当前作用域以确定参数的细节，所以在 5.3.0 以前的版本中不能用作函数的参数。如必须传递此值时，可将结果赋与一个变量，然后用此变量进行传递。

参见

func_get_arg() - 返回参数列表的某一项
func_get_args() - 返回一个包含函数参数列表的数组
ReflectionFunctionAbstract::getNumberOfParameters() - 获取参数数目

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User Contributed Notes 7 notes

down

jared at ws-db dot com ¶

16 years ago


Just a note for anyone wondering. This function doesn't include params that have a default value, unless you pass one in to overwrite the default param value. Not sure if that makes sense, so here's an example:


<?php

function helloWorld($ArgA, $ArgB="HelloWorld!") {

  return func_num_args();

}


// The following will return 1

$Returns1 = helloWorld("HelloWorld!");


// The following will return 2

$Returns2 = helloWorld("HelloWorld!", "HowdyWorld!");

?>

down

Dennis Robinson from basnetworks dot net ¶

12 years ago


This function comes in handy, and I believe is the only solution, when you have an optional parameter that can take any type of data.

For example:

<?php

// $data can be of any type, including null
function my_function($name, $data = null)
{
    if ($data !== null)
    {
        // Do something with $data
        // If you call my_function('something'), this WILL NOT be reached
        // If you call my_function('something', null), this WILL NOT be reached
    }
}

?>

The problem with the above function is that you will never be able to use null as the value for $data.  To fix this, use func_num_args() like so:

<?php

// $data can be of any type, including null
function my_function($name, $data = null)
{
    if (func_num_args() >= 2)
    {
        // Do something with $data
        // If you call my_function('something'), this WILL NOT be reached
        // If you call my_function('something', null), this WILL be reached
    }
}

?>

This solution works because func_num_args() reports exactly how many arguments were passed when the function was called.  It does not take into account when default argument values are used.

down

luisguillermo dot quevedovelez at gmail dot com ¶

10 years ago


I had defined a function function_name(){ ...} as a drupal callback.
I try to get how many params where passed

I got a Error and my Site falls down

I've replaced func_get_args() instead func_num_args() and my Site was restored.

I conclude you can not use  func_num_args() in callbacks.

Hope it helps.

down

tongcheong77 at gmail dot com ¶

5 years ago


If you are using PHP 7 and func_num_args is in your base class which you extended, you can pass your arguments with the 'spat' operator.

class Sql {

public function doGetWhere(...$args) {

$num_args = func_num_args();
      $args_list = func_get_args();

      echo '<pre>';
      var_dump($args_list);
      echo '<pre>';
  }
}

class Member extends Sql {

public function getWhere(...$args) {

   $this->doGetWhere(...$args);

      }
}

$member = new Member();
$member->getWhere('first_name','last_name','userlevel','email','where','email','=',$sub_email);

However, take note that if you 'new up' the 'Sql' class in your 'Member' class above, instead of extending it, you will not need to pass your arguments as a variable. Just my two cents. -Bruce tong

down

thalis at NOSPAMcs dot pitt dot edu ¶

20 years ago


The idea of func_get_args() is to construct functions of variable number of parameters like


<?php

function var_param_func(){

    if(func_num_args()==0){

        //do one thing

    }

    if(func_num_args()==1)

        //do another thing

        //get the args with func_get_args()

    }

}

?>

down

-1

ashley at dcs dot warwick dot ac dot uk ¶

20 years ago


If you want to pass the parameters on intact to another function, use func_get_args and call_user_func_array (careful - this one is only available in recent PHP versions).  For example:


<?php

/* Print an HTML tag.  This accepts a variable number of arguments:

   the first should be the name of the tag, followed by pairs of

   arguments that describe keys and values.  The values are printed

   with surrounding double quote characters.  */

function printTag() {

  $numArgs = func_num_args();

  if ($numArgs < 1) die("printTag given no arguments");

  

  echo "<" . func_get_arg(0);

  for ($i = 1; $i < $numArgs; $i+=2) {

    echo " " . func_get_arg($i);

    if ($i+1 < $numArgs)

      echo "=\"" . func_get_arg($i+1) . "\"";

  }

  echo ">";

  

}


/* Print an HTML tag with a newline on the end */

function printTagNL() {

  $args = func_get_args();

  call_user_func_array("printTag", $args);

  echo "\n";

}


printTagNL("input", "type", "hidden", "name", "SORTORDER", "value", $columnNo);

?>

down

-8

andy at arakka dot co dot th ¶

17 years ago


func_num_args() can be used in conjunction with named arguments, also. For example:


<?php

function DebugShow( $label, $value ) {

  echo "# " . $label ;

  if ( func_num_args() > 1 ) echo " = " . $value ;

  echo "<br>";

}

?>

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官方地址：https://www.php.net/manual/en/function.func-num-args.php

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PHP官方手册 - 互联网笔记

func_num_args

说明

返回值

更新日志

错误／异常

范例

注释

参见

User Contributed Notes 7 notes