Check a string for bad words? [duplicate] - php

Question

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Closed 10 years ago.
Possible Duplicate:
Efficient way to test string for certain words
I want to check if a string contains any of these words: ban, bad, user, pass, stack, name, html.
If it contains any of the words I need to echo the number of bad words
str = 'Hello my name is user';

Answer 1

I think something like this would work:
$badWords = array("ban","bad","user","pass","stack","name","html");
$string = "Hello my name is user.";
$matches = array();
$matchFound = preg_match_all(
"/\b(" . implode($badWords,"|") . ")\b/i",
$string,
$matches
);
if ($matchFound) {
$words = array_unique($matches[0]);
foreach($words as $word) {
echo "<li>" . $word . "</li>";
}
echo "</ul>";
}
This creates an array of banned words, and uses a regular expression to find instances of these words:
\b in the Regex indicates a word boundary (i.e. the beginning or end of a word, determined by either the beginning/end of the string or a non-word character). This is done to prevent "clbuttic" mistakes - i.e. you don't want to ban the word "banner" when you only want to match the word "ban".
The implode function creates a single string containing all your banned words, separated by a pipe character, which is the or operator in the Regex.
The implode portion of the Regex is surrounded with parentheses so that preg_match_all will capture the banned word as the match.
The i modifier at the end of the Regex indicates that the match should be case-sensitive - i.e. it will match each word regardless of capitalization - "Ban, "ban", and "BAN" will all match against the word "ban" in the $badWords array.
Next, the code checks if any matches were found. If there are, it uses array_unique to ensure only one instance of each word is reported, and then it outputs the list of matches in an unordered list.
Is this what you're looking for?

Answer 2

This is what you want.
function teststringforbadwords($string,$banned_words) {
foreach($banned_words as $banned_word) {
if(stristr($string,$banned_word)){
return false;
}
}
return true;
}
$string = "test string";
$banned_words = array('ban','bad','user','pass','stack','name','html');
if (!teststringforbadwords($string,$banned_words)) {
echo 'string is clean';
}else{
echo 'string contains banned words';
}

Answer 3

The \b in the pattern indicates a word boundary, so only the distinct
word "web" is matched, and not a word partial like "webbing" or "cobweb"
if (preg_match("/\bweb\b/i", "PHP is the web scripting language of choice.")) {
echo "A match was found.";
} else {
echo "A match was not found.";
}
if (preg_match("/\bweb\b/i", "PHP is the website scripting language of choice.")) {
echo "A match was found.";
} else {
echo "A match was not found.";
}
This is your best bet. As stated at the beginning you can control your regex.
This is directly from php.net

Answer 4

function check_words($text) {
$text=$text;
$bad_words = file('bad_words.txt');
$bad = explode(" | ",$bad_words[0]);
$b = '/\W' . implode('\W|\W', $bad) . '\W/i';
if(preg_match($b, $text)){
echo $text ." - Contain Bad words!"; other function here
} else {
echo $text ." - Not containing bad words :D";
// other function here
}
}
Example: check_words('He is good');
This works well although anything after the final / does not seem to get checked, e.g. http://www.mysite.com/thisbit, thisbit seems not to get checked for bad words.
It does work again how ever if it is typed like this: http://www.mysite.com/thisbit/, with the trailing /.
Not sure if this can be fixed or not.

Answer 5

function check_words($text) {
$text=$text;
$bad_words = file('bad_words.txt');
$bad = explode(" | ",$bad_words[0]);
$b = '/\W' . implode('\W|\W', $bad) . '\W/i';
if(preg_match($b, $text)){
echo $text ." - Contain Bad words!";
# - other function here
}
else{
echo $text ." - Not containing bad words :D";
# - other function here
}
}
# - Example
check_words('He is good');
Hope this can help.. you can put all the bad words in bad_words.txt file.
Arrange the bad words in txt as:
bad_words1 | bad_words2 | bad_words3 | bad_words4 ...
Note: you can also put something like:
bad words 1 | bad words 2 | bad words 3
as long as it is in the "|" format.