func_get_arg

Return an item from the argument list (PHP 4, PHP 5)
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. Function arguments are 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.

If arg_num is greater than the number of arguments actually passed, a warning will be generated and func_get_arg() will return FALSE.

注意:

因为本函数依赖于当前域来决定参数细节,因此不能用作函数参数。如果必须要传递这个值,将结果赋给一个变量,然后传递该变量。

<?php
function foo()
{
   
$numargs = func_num_args();
    echo
"Number of arguments: $numargs<br />\n";
    if (
$numargs >= 2) {
    echo
"Second argument is: " . func_get_arg(1) . "<br />\n";
    }
}

foo (1, 2, 3);
?>

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