random generated strings, possible to be equals?
<p>given a script that generates a string of 12 characters randomly generated, how many possibilities there are for two string to be equal?</p>

<pre><code>function rand_string( $length ) {
    $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";  

    $size = strlen( $chars );
    for( $i = 0; $i &lt; $length; $i++ ) {
        $str .= $chars[ rand( 0, $size - 1 ) ];
    }

    return $str;
}
</code></pre>
