<?php
$str = $_GET['str'];

function charfilter($string){
    $searchString = " ";
    $replaceString = "";
    $string = str_replace($searchString, $replaceString, $string);
    $string = preg_replace('/\.|\\\|\\/|\:|\*|\?|\"|\<|\>|\|/', '', $string);
    $string = preg_replace('/([\x80-\xff]*)/i', '', $string);
    return $string;
}
echo charfilter($str);