Anti SPAM: PHP compare similar string/text (with sorting)



function compare_similar_str($var_1, $var_2)
{
    $a1 = array();
    $a2 = array();
    $percent = 0;

    // You could add more delimiter/separators to fit your need
    $a1 = explode("\n", str_replace(' ', '', $var_1));
    $a2 = explode("\n", str_replace(' ', '', $var_2));

    sort($a1);
    sort($a2);

    $var_1 = implode('', $a1);
    $var_2 = implode('', $a2);

    similar_text($var_1, $var_2, $percent);

    return intval($percent);
}


/*
 * Replace symbols --> compare to achieve preliminary spam-proof
 */
function remove_symbols($this_str)
{
    $symbols = array('‘','’','：','，','；','。',',','"',';','、','～','＠','＃','＄','％','︿','＆','＊',
            '/','!','@','#','$','%',':','^','&','*','(',')','-','_','+','=','{','[','}',']','?',
            '<','>','~', "\n", '\\',
            '╳','○','☆','★','□','■','●','【','】','「','」','『','』','〈','〉',
            '【','】','「','」','『','』','〈','〉','《','》','〔','〕','｛','｝','↑','↓','←','→','↖','↗','↙','↘','╳','○','☆',
            '☻','☺','♠','♣','♥','♦','♪','♀','♂','㊣', "'", ' ',
            );

    $test = str_replace($symbols, '', $this_str);
    return $test;
}

Anti SPAM: PHP compare similar string/text (with sorting)

PHP: remove_symbols