PHP hex2bin() Function: Usage and Examples

Use hex2bin() when you need to decodes a hexadecimal digit string into binary bytes in a PHP application. The examples below show the actual operation and its limitations.

What Is hex2bin() in PHP?

Decodes a hexadecimal digit string into binary bytes. The exact signature supported by your installation depends on its PHP version and enabled extensions.

Its syntax is:

hex2bin(string $string): string|false

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

echo hex2bin("4869");

Output:

Hi

Example 2: Different Input or Behavior

<?php

echo bin2hex(hex2bin("00ff"));

Output:

00ff

Practical Example: Applying the Function

<?php

$storedHex = "414243"; if (ctype_xdigit($storedHex) && strlen($storedHex) % 2 === 0) echo hex2bin($storedHex);

Output:

ABC

Important Behavior and Edge Cases

The input must have an even number of valid hexadecimal digits. Encoding is not encryption.

Comparison With Related Functions

Common Beginner Mistakes

Key Takeaways

• Decodes a hexadecimal digit string into binary bytes.
• The input must have an even number of valid hexadecimal digits. Encoding is not encryption.
• bin2hex() encodes bytes into hex text; hex2bin() decodes the text.

Use hex2bin() for the specific operation demonstrated above. Check its prerequisites and handle failure conditions before using it with production data.