Filter spam words in a string - PHP snippet

This php snippet check if a string contain spam words contained in text file and filter them.

function is_spam($text, $file, $split = ':', $regex = false){ 
    $handle = fopen($file, 'rb'); 
    $contents = fread($handle, filesize($file)); 
    fclose($handle); 
    $lines = explode("\n", $contents); 
    $arr = array(); 
    foreach($lines as $line){ 
        list($word, $count) = explode($split, $line); 
        if($regex) 
            $arr[$word] = $count; 
        else 
            $arr[preg_quote($word)] = $count; 
    } 
    preg_match_all("~".implode('|', array_keys($arr))."~", $text, $matches); 
    $temp = array(); 
    foreach($matches[0] as $match){ 
        if(!in_array($match, $temp)){ 
            $temp[$match] = $temp[$match] + 1; 
            if($temp[$match] >= $arr[$word]) 
                return true; 
        } 
    } 
    return false; 
} 

$file = 'spam.txt'; 
$str = 'This string has the word viagra and sex get viagra see viagra'; 
if(is_spam($str, $file)) 
    echo 'this is spam'; 
else 
    echo 'this is not spam';