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    md5_file

    (PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

    md5_file — Calcola l'hash md5 del file dato

    Descrizione

    md5_file(string $filename, bool $raw_output = false): string

    Calcola l'hash MD5 del file specificato dal parametro filename utilizzando il » RSA Data Security, Inc. MD5 Message-Digest Algorithm, e restituendo quell'hash. L'hash รจ un numero esadecimale di 32 caratteri.

    Elenco dei parametri

    filename

    Il nome del file

    raw_output

    Quando true, restituisce il digest nel formato binario raw con una dimensione di 16.

    Valori restituiti

    Restituisce una stringa in caso di successo, false in caso contrario.

    Esempi

    Example #1 Esempio di uso di md5_file()

    <?php
    $file     = 'php-5.3.0alpha2-Win32-VC9-x64.zip';

    echo     'MD5 file hash of ' . $file . ': ' . md5_file($file);
    ?>

    Vedere anche:

    • md5() - Calcola il valore md5 di una stringa
    • sha1_file() - Calcola l'hash sha1 di un file
    • crc32() - Calcola il crc32 polinomiale di una stringa

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    User Contributed Notes 5 notes

    up
    77
    Chris
    15 years ago
    If you just need to find out if two files are identical, comparing file hashes can be inefficient, especially on large files.  There's no reason to read two whole files and do all the math if the second byte of each file is different.  If you don't need to store the hash value for later use, there may not be a need to calculate the hash value just to compare files.  This can be much faster:

    <?php
    define    ('READ_LEN', 4096);

    if(    files_identical('file1.txt', 'file2.txt'))
        echo     'files identical';
    else
        echo     'files not identical';

    //   pass two file names
    //   returns TRUE if files are the same, FALSE otherwise
    function files_identical($fn1, $fn2) {
        if(    filetype($fn1) !== filetype($fn2))
            return     FALSE;

        if(    filesize($fn1) !== filesize($fn2))
            return     FALSE;

        if(!    $fp1 = fopen($fn1, 'rb'))
            return     FALSE;

        if(!    $fp2 = fopen($fn2, 'rb')) {
                fclose($fp1);
            return     FALSE;
        }

            $same = TRUE;
        while (!    feof($fp1) and !feof($fp2))
            if(    fread($fp1, READ_LEN) !== fread($fp2, READ_LEN)) {
                    $same = FALSE;
                break;
            }

        if(    feof($fp1) !== feof($fp2))
                $same = FALSE;

            fclose($fp1);
            fclose($fp2);

        return     $same;
    }
    ?>
    up
    11
    lukasamd at gmail dot com
    12 years ago
    It's faster to use md5sum than openssl md5:

    <?php
    $begin     = microtime(true);

    $file_path = '../backup_file1.tar.gz';
    $result = explode("  ", exec("md5sum $file_path"));
    echo     "Hash = ".$result[0]."<br />";

    # Here 7 other big files (20-300 MB)

    $end = microtime(true) - $begin;
    echo     "Time = $end";
    # Time = 4.4475841522217

    #Method with openssl
    # Time = 12.1463856900543
    ?>

    About 3x faster
    up
    0
    smartin
    16 years ago
    In response to using exec instead for performance (Nov 13 2007 post), It looks like the performance depends on the size of the file.  See the results below using the same script from the original post.  The first hash is with md5_file and the second is with openssl md5.

    With a 1MB file:
    Hash = df1555ec0c2d7fcad3a03770f9aa238a; time = 0.005006
    Hash = df1555ec0c2d7fcad3a03770f9aa238a; time = 0.01498

    With a 2MB file:

    Hash = 4387904830a4245a8ab767e5937d722c; time = 0.010393
    Hash = 4387904830a4245a8ab767e5937d722c; time = 0.016691

    With a 10MB file:

    Hash = b89f948e98f3a113dc13fdbd3bdb17ef; time = 0.241907
    Hash = b89f948e98f3a113dc13fdbd3bdb17ef; time = 0.037597

    Performance seems to change proportionally with the file size.  Judging from the previous post's default file name (.mov) he/she was probably dealing with a large file.  These are just quick tests and far from a perfect benchmark, but you might want to test your own files before assuming that the openssl solution is faster (ie, if working with small text files vs. movies, etc)
    up
    0
    potsed [at] gmail [dot] com
    17 years ago
    Heres a function to give an md5 for an entire directory..

    function MD5_DIR($dir)
    {
        if (!is_dir($dir))
        {
            return false;
        }
       
        $filemd5s = array();
        $d = dir($dir);

        while (false !== ($entry = $d->read()))
        {
            if ($entry != '.' && $entry != '..')
            {
                 if (is_dir($dir.'/'.$entry))
                 {
                     $filemd5s[] = MD5_DIR($dir.'/'.$entry);
                 }
                 else
                 {
                     $filemd5s[] = md5_file($dir.'/'.$entry);
                 }
             }
        }
        $d->close();
        return md5(implode('', $filemd5s));
    }
    up
    -7
    richard at interlink dot com dot au
    19 years ago
    For those of you with PHP 4 that want to output the "raw" 128 bit hash, all you need to do is send it to pack to convert the hex string into the raw output.

    ie:
    $filename="checkthisfile.bin";
    $rawhash=pack("H*",md5_file($filename));
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