PHP md5_file() Function

Complete PHP String Reference

Definition and Usage

The md5_file() function calculates the MD5 hash of a file.

The md5_file() function uses the RSA Data Security, Inc. MD5 Message-Digest Algorithm.

From RFC 1321 - The MD5 Message-Digest Algorithm: "The MD5 message-digest algorithm takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input. The MD5 algorithm is intended for digital signature applications, where a large file must be "compressed" in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA."

This function returns the calculated MD5 hash on success, or FALSE on failure.

Syntax

md5_file(file,raw)

Example 1

<?php
$filename = "test.txt";
$md5file = md5_file($filename);
echo $md5file;
?>  

The output of the code above will be:

5d41402abc4b2a76b9719d911017c592

Example 2

Store the MD5 hash of "test.txt" in a file:

<?php
$md5file = md5_file("test.txt");
file_put_contents("md5file.txt",$md5file);
?>

In this example we will test if "test.txt" has been changed (that is if the MD5 hash has been changed):

<?php
$md5file = file_get_contents("md5file.txt");
if (md5_file("test.txt") == $md5file)
  {
  echo "The file is ok.";
  }
else
  {
  echo "The file has been changed.";
  }
?>  

The output of the code above could be:

The file is ok.

Complete PHP String Reference

Get Your Diploma! W3Schools' Online Certification Program is the perfect solution for busy professionals who need to balance work, family, and career building. The HTML Certificate is for developers who want to document their knowledge of HTML, XHTML, and CSS. The ASP Certificate is for developers who want to document their knowledge of ASP, SQL, and ADO.

Jump to: Top of Page or HOME or Printer friendly page

W3Schools provides material for training only. We do not warrant the correctness of its contents. The risk from using it lies entirely with the user. While using this site, you agree to have read and accepted our terms of use and privacy policy.

Copyright 1999-2008 by Refsnes Data. All Rights Reserved.

W3Schools was converted to XHTML in December 1999