PHP validate input alphanumeric plus a few symbols

Question

Need a way to validate an input field (in PHP) so it can contain only the following:

Any letter
Any number
any of these symbols: - (dash) _ (underscore) @ (at) . (dot) or a SPACE

Field can start or end with any of these (but not a space, but I can trim it before passing into validation function), and contain none, one, or any number (so just a check to make sure everything in the input is one of the above).

I would like to be able to do something like this:

funcion is_valid ( $in_form_input ) {
  // returns true or false
}

if ( is_valid($_POST['field1']) ) {
  echo "valid";
} else {
  echo "not valid";
}

score 4 · Accepted Answer · answered Feb 20 '10 at 19:10

4

return !preg_match('/[^-_@. 0-9A-Za-z]/', $in_form_input);

answered Feb 20 '10 at 19:10

codeholic

5,680
3
23
43

There was basically the same question http://stackoverflow.com/questions/2284061/how-do-i-write-a-perl-regular-expression-that-will-match-a-string-with-only-these/2284442#2284442 – codeholic Feb 20 '10 at 19:11
wrapped this into a function and it worked as needed - thanks! – OneNerd Feb 20 '10 at 19:17

score 3 · Answer 2 · answered Nov 28 '12 at 08:50

The Best way would be to use like this :-

$str = "";
function validate_username($str) 
{
    $allowed = array(".", "-", "_", "@", " "); // you can add here more value, you want to allow.
    if(ctype_alnum(str_replace($allowed, '', $str ))) {
        return $str;
    } else {
        $str = "Invalid Username";
        return $str;
    }
}

score 3 · Answer 3 · answered Feb 20 '10 at 19:12

3

Use preg_match():

if (preg_match('!^[\w @.-]*$!', $input)) {
  // its valid
}

Note: \w is synonymous to [a-zA-Z0-9_].

answered Feb 20 '10 at 19:12

cletus

616,129
168
910
942

PHP validate input alphanumeric plus a few symbols

3 Answers3

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