Efficient way to test string for certain words

Question

I have a bunch of banned words and want to check if string A contains any of these words.

For example:

$banned_words = \"dog cat horse bird mouse mon         


        

Answer 1

$badwords = array('dog','cat','horse','bird','mouse','monkey');
$content= "The quick brown fox jumped over the lazy dog";
$content = str_replace($badwords, 'has_badwords' $content);
if (strpos($content, 'has_badwords') !== false) {
    echo 'true';
}

Answer 2

It would be a whole lot easier to create an array of banned words and then use str_replace with that array, like so:

$banned_words = array('dog', 'cat', 'horse', 'bird', 'mouse', 'monkey', 'blah', 'blah2', 'blah3');
$string_A = "The quick brown fox jumped over the lazy dog";
echo str_replace($banned_words, "***", $string_A);

Will output: The quick brown fox jumped over the lazy ***

Answer 3

I just developed a function that can filter out the bad words:

function hate_bad($str)
{
    $bad=array("shit","ass");
    $piece=explode(" ",$str);
    for($i=0;$i < sizeof($bad); $i++)
    {
        for($j=0;$j<sizeof($piece);$j++)
        {
            if($bad[$i]==$piece[$j])
            {
                $piece[$j]=" ***** ";
            }
        }
    }

    return $piece;
}

and call it like this:

$str=$_REQUEST['bad'];// here bad is the name of tex field<br/><br/>
$good=hate_bad($str);  <br/>  

if(isset($_REQUEST['filter']))// 'filter' name of button
{
    for($i=0;$i<sizeof($good);$i++)
    {<br/>
        echo $good[$i];
    }
}

Answer 4

Wouldn't it be better if the $banned_w would be an array?

Then you could explode() the string you want to check for banned words, then for every exploded piece use in_array() to check if it's a banned word.

Edit: You could use: similar_text for the comparisons, if one modifies the bad word a bit.

Answer 5

if (preg_match('~\b(' . str_replace(' ', '|', $banned_words) . ')\b~', $string_A)) {
    // there is banned word in a string
}

Answer 6

You can use str_ireplace, to check for bad words or phrases. This can be done in a single line of PHP code without the need for nested loops or regex as follows:

$banstring = ($string != str_ireplace($badwords,"XX",$string))? true: false;

This approach has the added benefit of being case insensitive. To see this in action, you could implement the check as follows:

$string = "The quick brown fox jumped over the lazy dog";
$badwords = array('dog','cat','horse','bird','mouse','monkey');
$banstring = ($string != str_ireplace($badwords,"XX",$string))? true: false;
if ($banstring) {
    echo 'Bad words found';
} else {
    echo 'No bad words in the string';
}

If the list of bad words is a string rather than an array (as in the question), then the string can be turned into an array as follows:

$banned_words = "dog cat horse bird mouse monkey"; //etc
$badwords = explode(" ", $banned_words);