Returns the number of arguments passed into the current user-defined function. func_num_args() will generate a warning if called from outside of a user-defined function.
| <?php
function foo() {
    $numargs = func_num_args();
    echo "Number of arguments: $numargs\n";
} 
foo (1, 2, 3);    // Prints 'Number of arguments: 3'
?> | 
func_num_args() may be used in conjunction with func_get_arg() and func_get_args() to allow user-defined functions to accept variable-length argument lists.