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PHP Quiz PHP CertificatePHP md5_file() Function
Example
Calculate the MD5 hash of the text file "test.txt":
<?php
$filename = "test.txt";
$md5file = md5_file($filename);
echo $md5file;
?>
$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:
|
Technical Details
| Return Value: | Returns the calculated MD5 hash on success, or FALSE on failure |
|---|---|
| PHP Version: | 4+ |
| 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);
?>
$md5file = md5_file("test.txt");
file_put_contents("md5file.txt",$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.";
}
?>
$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
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