PHP supports variable-length argument function. It means you can pass 0, 1 or n number of arguments in the function. To do so, you need to use 3 ellipses (dots) before the argument name.

A simple example of a PHP variable-length argument function.

Example

<?php  
function addCal(...$numbers) {  
    $sum = 0;  
    foreach ($numbers as $n) {  
        $sum += $n;  
    }  
    return $sum;  
}  
echo add(1,2,3,4);  
?>  

Output:10

1. func_num_args()

• This function returns the number of the argument passed into the current user-defined function. The return type is an integer.
• Func_num_args() will generate a warning if called from outside of a user-defined function.

Syntax

int func_num_args(void)

Example

<?php
   function callMe()
   {
      $value = func_num_args();
      echo "Number of arguments : ".$value;
   }
   callMe(1,2,3,4);
?>

Output  :  

Number of arguments : 4

2. func_get_arg()

• Returns an item from the argument list.

Syntax

mixed func_get_arg(int arg_num)

• Returns the argument which is at the arg_num’th offset into a user-defined function’s argument list.
• The function argument is counted starting from zero.
• func_get_arg() will generate a warning if called from outside of a function definition. This function cannot be used directly as a function parameter instead, its result may be assigned to a variable, which can then be passed to the function.

Example

<?php
 function callMe()
 {
   $num_arg = func_num_args();
   echo "Number of arguments : ".$num_arg."<br/>";
   if($num_arg >= 2)
   {
     echo "Seccond arguments is : ".func_get_arg(1);
   }
 }
 callMe(1,2,3,4);
?>

Output  :

Number of arguments : 4

Seccond arguments is : 2

3. func_get_args()

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

Syntax

array func_get_args(void)

Example

<?php
  function callMe()
  {
    $num_args = func_num_args();
    if($num_args > 0)
    {
      $num = func_get_args();
      foreach($num as $value)
      {
        echo $value."<br/>";
      }
    }
  }
 callMe("Hello","World");
?>

Output  :

Hello

World