CODEWITHSUNDEEP
phpvalidation
WildBill
WildBill

Reputation: 9291

How to validate pattern in input string?

If I had a webpage and I neeed to ensure user input for a variable is only letters (upper and lower), numbers and dashes and the length had to be exactly 20 chars in length, how would one perform that?

Upvotes: 3

Views: 5700

Answers (3)

Marc
Marc

Reputation: 257

You can use regular expressions. See preg_match.

Your regular expression could look something like:

/^[A-Za-z0-9\-]{20}$/

or

/^[\w-]{20}$/

Upvotes: 3

patocardo
patocardo

Reputation: 83

if you don't trust in regexp because of performance you may use the following, which will take longer:

function checkalphanum($str){
    $allowed = "0123456789abcdefghijklmnopqrstuvwxyz_-ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    if(strlen($str) == 20){ return false;}
    for($i=0; $i < count($str); $i++){
        if(strpos($allowed, substr($str, $i, 1)) == -1){
            return false;
        }
    }
    return true;
}

Upvotes: 0

spencercw
spencercw

Reputation: 3358

This is pretty easy to do using regular expressions:

echo preg_match('/^[0-9a-zA-Z\-]{20}$/', 'abcd');
0
echo preg_match('/^[0-9a-zA-Z\-]{20}$/', 'abcdefghijkmlnopqrst');
1

Upvotes: 5

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