PHP md5_file() function

Example

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

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

The above code will output:

d41d8cd98f00b204e9800998ecf8427e

Definition and usage

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

The md5_file() function uses RSA data security, including the MD5 message digest algorithm.

Explanation from RFC 1321 - MD5 message digest algorithm: The MD5 message digest algorithm takes information of any length as an input value and converts it into a 128-bit length "fingerprint information" or "message digest" value to represent this Enter a value and get the converted value as the result. The MD5 algorithm is primarily designed for digital signature applications where larger files are encrypted using a public key in a cryptographic system such as RSA. (done by setting a private key) before compressing in a secure manner.

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

grammar

 md5_file( file,raw )

parameter	describe
file	Required. Specifies the file to be calculated.
raw	Optional. A Boolean value specifying the hexadecimal or binary output format: TRUE - raw 16-character binary format FALSE - Default. 32-character hexadecimal number

technical details

Return value:	Returns the calculated MD5 hash on success, or FALSE on failure.
PHP version:	4.2.0+
Update log:	In PHP 5.0, the raw parameter becomes optional. Since PHP 5.1, md5_file() can be used through wrappers. For example: md5_file("http://w3cschool.cc/..")

More examples

Example 1

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

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

Detect whether "test.txt" has been changed (i.e. whether 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 above code will output:

The file is ok.