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PHP md5_file() Function

PHP String Reference PHP String Reference

Example

Calculate the MD5 hash of the text file "test.txt":

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

The output of the code above will be:

d41d8cd98f00b204e9800998ecf8427e


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."

To calculate the MD5 hash of a string, use the md5() function.


Syntax

md5_file(file,raw)

Parameter Description
file Required. The file to be calculated
raw Optional. A boolean value that specifies hex or binary output format:
  • TRUE - Raw 16 character binary format
  • FALSE - Default. 32 character hex number

Technical Details

Return Value: Returns the calculated MD5 hash on success, or FALSE on failure
PHP Version: 4.2.0+
Changelog: The raw parameter was added in PHP 5.0

As of PHP 5.1, it is possible to use md5_file() with wrappers, e.g. md5_file("http://w3schools.com/..")


More Examples

Example 1

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

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

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.



PHP String Reference PHP String Reference

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