Bad word check in PHP using stripos

Question

I implemented this "bad word" check function in php:

# bad word detector
function check_badwords($string) {
    $badwords = array(a number of words some may find inappropriate for SE);
    foreach($badwords as $item) {
        if(stripos($string, $item) !== false) return true;
    }
    return false;
}

It works alright, except I'm having a little problem. If the $string is:

Who is the best guitarist ever?

...it returns true, because there is a match with Who ($string) and ho (in $badwords array). How could the function be modified so that it only checks for complete words, and not just part of words?

check_badwords('She is a ho'); //should return true
check_badwords('Who is she?'); //should return false

Thanks!

https://stackoverflow.com/questions/26177013/filter-exact-word-not-wholeword this should help. — deg, Sep 05 '17 at 21:39
[How to find full words only in string](https://stackoverflow.com/questions/8898825/how-to-find-full-words-only-in-string) as another duplicate. — spectras, Sep 05 '17 at 21:44
Your array of words isn't sufficiently exhaustive. Without even scrolling I can already tell that you're missing a whole class of compound words beginning with anus. Better to just split the string on space and check each word to see if it has an entry in urban dictionary. — Don't Panic, Sep 05 '17 at 22:09
Without sounding like a tw*t: Is it really necessary to post a big list of profanity / swear words on SO to get a programming question across? The problem could still be solved if the array contained `unicorn`, `donut` and `icecream`. — ccKep, Sep 05 '17 at 22:15
[Clbuttic rookie mistake.](https://en.wikipedia.org/wiki/Scunthorpe_problem) — Sammitch, Sep 05 '17 at 22:24

ren.rocks · Answer 1 · 2017-09-05T21:42:31.290

1

You probably would like to replace stripos with preg_match

if you can make it a better regex, more power to you:

preg_match("/\s($string){1}\s/", $input_line, $output_array);

edited Sep 05 '17 at 21:42

answered Sep 05 '17 at 21:39

ren.rocks

772
1
7
22

`“ass”` => `false` – spectras Sep 05 '17 at 21:40
The quick solution of course ignores start and end of sentence, or any adjacent punctuation. – deg Sep 05 '17 at 21:41
@deg you are right. – ren.rocks Sep 05 '17 at 21:42

axiac · Accepted Answer · 2017-09-06T05:51:17.007

In order to check for complete words you should use regular expressions:

function check_badwords($string)
{
    $badwords = array(/* the big list of words here */);
    // Create the regex
    $re = '/\b('.implode('|', $badwords).')\b/';
    // Check if it matches the sentence
    return preg_match($re, $string);
}

How the regex works

The regular expression starts and ends with the special sequence \b that matches a word boundary (i.e. when a word character is followed by a non-word character or viceversa; the word characters are the letters, the digits and the underscore).

Between the two word boundaries there is a subpattern that contains all the bad words separated by |. The subpattern matches any of the bad words.

If you want to know what bad word was found you can change the function:

function check_badwords($string)
{
    $badwords = array(/* the big list of words here */);
    $re = '/\b('.implode('|', $badwords).')\b/';
    // Check for matches, save the first match in $match
    $result = preg_match($re, $string, $match);
    // if $result is TRUE then $match[1] contains the first bad word found in $string
   return $result;
}

Could we just use placeholder for those words instead? I can't think of a logical reason to have profanity / swearing anywhere on SO, even if this is a valid question in and off itself. — ccKep, Sep 05 '17 at 22:11

score 0 · Answer 3 · answered Sep 05 '17 at 22:17

0

You can even lowercase the $string and then instead using stripos or even a regular expression, just use in_array(). That'd match against the whole word.

answered Sep 05 '17 at 22:17

MarkSkayff

1,334
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14

Bad word check in PHP using stripos

3 Answers3