Detailed explanation of variable length parameter processing function in PHP

This article mainly introduces the PHP variable-length parameter processing function, and analyzes the functions and usage of the three variable-length parameter processing functions func_num_args(), func_get_arg() and func_get_args() combined with examples. Friends who need it can For reference,

is 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)

<?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 )

<?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);
?>

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