func_num_args

(PHP 4, PHP 5, PHP 7)

func_num_args — Returns the number of arguments passed to the function

说明

int func_num_args ( void )

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

Example #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

Example #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

Note:

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

用户评论:

[#1] luisguillermo dot quevedovelez at gmail dot com [2012-03-13 07:32:48]

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.

[#2] Dennis Robinson from basnetworks dot net [2009-06-29 21:29:25]

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.

[#3] jared at ws-db dot com [2005-09-06 09:46:41]

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!"); ?>

[#4] andy at arakka dot co dot th [2005-05-11 19:16:50]

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>"; } ?>

[#5] ashley at dcs dot warwick dot ac dot uk [2002-04-17 04:40:26]

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); ?>

[#6] thalis at NOSPAMcs dot pitt dot edu [2002-03-29 12:05:31]

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() } } ?>