PHP Kütüphanesi

<?php
$yer = $_GET["do"]; 
header("Location:$yer");
?>

function mail_kontrol($email) { 
if (!eregi ("^([a-z0-9_]|\\-|\\.)+@(([a-z0-9_]|\\-)+\\.)+[a-z]{2,4}$", $email)) 
die ("E-Mail Adresiniz Geçersiz"); 
}

mail_kontrol("[email protected]");

function yonlendir($yol) 
{ 
    if(!headers_sent()) 
         header("Location : $yol"); 
    else 
        echo "<script language=\"JavaScript\">window.location.href = '$yol';</script>"; 
    exit; 
}

yonlendir('yenisayfa.php');

function createRandomPassword() { 

    $chars = "abcdefghijklmnoprstuvyz0123456789"; 
    srand((double)microtime()*1000000); 
    $i = 0; 
    $pass = '' ; 

    while ($i <= 5) { 
        $num = rand() % 6; 
        $tmp = substr($chars, $num, 1); 
        $pass = $pass . $tmp; 
        $i++; 
    } 

    return $pass; 

}

function GetIP(){ 
    if(getenv("HTTP_CLIENT_IP")) { 
        $ip = getenv("HTTP_CLIENT_IP"); 
    } elseif(getenv("HTTP_X_FORWARDED_FOR")) { 
        $ip = getenv("HTTP_X_FORWARDED_FOR"); 
        if (strstr($ip, ',')) { 
            $tmp = explode (',', $ip); 
            $ip = trim($tmp[0]); 
        } 
    } else { 
        $ip = getenv("REMOTE_ADDR"); 
    } 
    return $ip; 
}

function toUpperCase( $input ) 
{ 
    return strtoupper( strtr( $input,'ğüşıiöç', 'ĞÜŞIİÖÇ') ); 
}

function toLowerCase( $input ) 
{ 
    return strtolower(strtr( $input,'ĞÜŞIİÖÇ','ğüşıiöç')); 
}

<?php 
function degis($veri) { 
$degistir = strtr($veri,"ÜŞÇİĞüöşçığ","USCIGuoscig"); 
return $degistir; 
} 
?>