Detailed explanation of PHP variable length parameter processing function

The example in this article describes the php variable length parameter processing function. Share it with everyone for your reference, the details are as follows:

Like C++, functions containing variable parameters can also be processed in PHP. The principle is the same, and a function is needed to specifically process the parameter list. PHP provides three related functions:

1. func_num_args() -- Returns the number of parameters passed to the function

int func_num_args ( void )

Example:

function open_database($DB, $cache_size_or_values=null, $cache_size=null)
{
  switch (function_num_args())
  {
    case 1:
      $r = select_db($DB);
      break;
    case 2:
      $r = select_db($DB, $cache_size_or_values);
      break;
    case 3:
      $r = select_db($DB, $cache_size_or_values, $cache_size);
      break;
  }
  return is_resource($r);
}

##2. func_get_arg() -- Return the specified parameter

mixed func_get_arg (int arg_num)

The arg_num of the first parameter in the parameter list is 0

<?php
  function some_func($a, $b)
  {
    for($i = 0; $i<func_num_args(); ++$i)
    {
      $param = func_get_arg($i);
      echo "the param is $param\n"
    }
  }
  some_func(1,3,5,7,9);
?>

3. func_get_args() -- Returns the parameter list in the form of an array

array func_get_args ( void )

Example:

<?php
  function some_other_func($a, $b)
  {
    $param = func_get_args();
    $param = join(", ", $param);  // 分解显示
    echo "the arglist is: $param\n";
  }
  some_other_func(1,3,5,7,9);
?>

For more detailed explanations of PHP variable-length parameter processing functions, please pay attention to the PHP Chinese website!