PHP func_num_args() Function: Usage and Examples

Use func_num_args() when you need to returns the number of arguments actually passed to the current user-defined function in a PHP application. The examples below show the actual operation and its limitations.

What Is func_num_args() in PHP?

Returns the number of arguments actually passed to the current user-defined function. The exact signature supported by your installation depends on its PHP version and enabled extensions.

Its syntax is:

func_num_args(): int

Parameters and return value: The parameter types, optional arguments, references, and return type are shown in the signature above. Optional parameters are marked with an ellipsis in this reference signature.

Example 1: Basic Usage

<?php

function describeArgs($firstValue = null, $secondValue = null) { return func_num_args(); } echo describeArgs("one");

Output:

1

Example 2: Different Input or Behavior

<?php

function countProvided($firstValue = null, $secondValue = null) { return func_num_args(); } echo countProvided("one","two");

Output:

2

Practical Example: Applying the Function

<?php

function formatOptional($value, $precision = 2) { return func_num_args() === 1 ? "Default precision" : "Explicit precision"; } echo formatOptional(12.5);

Output:

Default precision

Important Behavior and Edge Cases

It must be called from inside a user-defined function; parameter defaults do not count as passed arguments.

Comparison With Related Functions

Common Beginner Mistakes

Key Takeaways

• Returns the number of arguments actually passed to the current user-defined function.
• It must be called from inside a user-defined function; parameter defaults do not count as passed arguments.
• func_get_args() obtains the actual arguments; func_num_args() counts them.

Use func_num_args() for the specific operation demonstrated above. Check its prerequisites and handle failure conditions before using it with production data.