function generatorstring($count)
{
    $karakter = '0123456789abcdefghijklmnopqrstuvwxyz';
    $length = 7;
    $randomString = '';

    for ($i=0; $i <$count ; $i++)
    {
        for ($i = 0; $i < $length; $i++)
        {
            $randomString .= $karakter[rand(0, strlen($karakter) - 1)];
        }
    }

    return $randomString;
}

echo generatorstring(3);

'As6s8Xs',
'zE71jnM',
'ak9a71b',

function generatorstring($length = 7){
    $karakter = '0123456789abcdefghijklmnopqrstuvwxyz';
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $karakter[rand(0, strlen($karakter) - 1)];
    }
    return $randomString;
}

for ($i = 0; $i < 3; $i++)
    $res[] = generatorstring();

function createRandomStringArray($count) {
    for ($i = 0; $i < $count; $i++)
        $res[] = generatorstring();
    return $res;
}