(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
md5_file — Calculates the md5 hash of a given file
$filename, bool $binary = false): string|false
   Calculates the MD5 hash of the file specified by the
   filename parameter using the
   » RSA Data Security, Inc. 
   MD5 Message-Digest Algorithm, and returns that hash.
   The hash is a 32-character hexadecimal number.
  
filenameThe filename
binary
       When true, returns the digest in raw binary format with a length of
       16.
      
   Returns a string on success, false otherwise.
  
Example #1 Usage example of md5_file()
<?php
$file = 'php-5.3.0alpha2-Win32-VC9-x64.zip';
echo 'MD5 file hash of ' . $file . ': ' . md5_file($file);
?>