CODEWITHSUNDEEP
phppreg-match
ntan
ntan

Reputation: 2205

php preg_match fail to return not matching

i have the following php code for validate First Name, Last Name

if (preg_match("/^[A-Za-z\p{Greek}\s]+$/u", "Hello & World!", $m)) 
{
    //validation pass
    echo "validation pass";
}
else
{
    //validation failed
    var_dump($m);
    echo "validation failed";
}

The problem is that i was expecting on $m[0] to found the non matching elements so echo a message like

echo "{$m[0]} is not allow character(s)";

but the $m variable is an empty array

Any help appreciated Thanks

Upvotes: 2

Views: 377

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626929

You can't do that with a single regex, as the non-matching chars are not stored after a match is failed.

You may use a kind of an inverted pattern after failing a match, like

$s = "Hello & World!";
if (preg_match("/^[A-Za-z\p{Greek}\s]+$/u", $s)) {
    echo "validation pass"; //validation pass
}
else {
    if (preg_match_all('~[^A-Za-z\p{Greek}\s]~u', $s, $m)) { //validation failed
        var_dump($m[0]);
    }
    echo "validation failed";
}

See the PHP demo. Output:

array(2) {
  [0]=>
  string(1) "&"
  [1]=>
  string(1) "!"
}
validation failed

The [^A-Za-z\p{Greek}\s] pattern is a negated character class matching any char other than the one(s) defined in the class: ASCII and Greek letters and whitespaces.

Upvotes: 1

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