PHP Function to create random alphanumeric strings

RandomString

/**
 * function to generate random strings
 * @param 		int 	$length 	number of characters in the generated string
 * @return 		string	a new string is created with random characters of the desired length
 */
function RandomString($length = 32) {
    $randstr;
    srand((double) microtime(TRUE) * 1000000);
    //our array add all letters and numbers if you wish
    $chars = array(
        'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'p',
        'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '1', '2', '3', '4', '5',
        '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 
        'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z');

    for ($rand = 0; $rand <= $length; $rand++) {
        $random = rand(0, count($chars) - 1);
        $randstr .= $chars[$random];
    }
    return $randstr;
}

Although it works, it prints an error: "Notice: Undefined variable: randstr in [...] on line 18".
This can be fixed by editing line 7 from $randstr; to $randstr = "";

it works for me
if u having error on randstr.
then change to this
function RandomString($length = 32) {
$randstr = ' ';
then it will work .