在php中过滤正确的单词和适当的语言英语

Question

i am building a system in which user comment and earn credit. to get credit quickly user add comment such as "fffff" , "niceeeeeeeeee", "greeeeeeaaaatt", "aaaa", "b" etc...
Is there anyway to filter out these comments. any suggestion will be appreciated.

Answer 1

You could check to see if the user's input contains 3 consecutive characters using a regular expression (since I'm not aware of any words in english which have 3 of the same letter in a row)

$user_input = "niceeeeeeeeeeee";

if (preg_match("/([A-Za-z])\\1\\1/", $user_input)) {
    echo "String contains the same letter 3 times in a row and is not valid";
} else {
    echo "String is ok!";
}

This would match "niceee", "greeeat", "aaaa" etc. or any string with the same letter 3 or more times in a row. If you want to check users' input against multiple patterns, you could put your regular expressions in an array and check them all e.g.:

$patterns = [
    "/(.)\\1\\1/",            // any character (not just letters) 3+ times in a row
    "/^.$/",                  // a single character
    "/.{15,}/",               // contains a word longer than 15 characters
    "/([A-Za-z]{2,})\\1\\1/"  // 2 letters alternating e.g. "abababab"
];

foreach( $patterns as $pattern ){
    if (preg_match($pattern, $user_input)) {
        echo "This is an invalid string";
    }
}

Or if you don't have too many patterns (and you aren't concerned with readability) you could just concatenate all the patterns together with |.

if (preg_match("/(.)\\1\\1|^.$|.{15,}|([A-Za-z]{2,})\\2\\2/", $user_input)) {
    echo "This is an invalid string";
}