CODEWITHSUNDEEP
c#regex
Confused Newbie
Confused Newbie

Reputation: 29

RegEx matching a something between two numbers

I am trying to match results that contain either 4 numbers or 6 numbers, nothing else. I have tried using (?!5) or (?!\d) at the end but it still matches input of 5 numbers, I feel like I have tried everything.

It returns the second test as a match.

Tests:

 [Test]
  [TestCase("1234", Result=true)]
  [TestCase("12345", Result=false)]
  [TestCase("a234", Result=false)]
  [TestCase("", Result=false)]

Code:

using System.Text.RegularExpressions;


public class Program 
{
    public static bool ValidatePIN(string pin) 
    {
        string pattern = @"[1-9]{4}|[1-9]{6}(?!5)";
        Regex rg = new Regex(pattern); 
        Match match = rg.Match(pin);
        
        if (match.Success) {
                return true;
            } else {
                return false;
            }
    }
}

Upvotes: 1

Views: 108

Answers (2)

AnGG
AnGG

Reputation: 821

    public static bool IsValid(string s)
    {
        return Regex.IsMatch(s, "^([\\d]{4}|[\\d]{6})$");
    }

Upvotes: 1

Dmitrii Bychenko
Dmitrii Bychenko

Reputation: 186668

It seems, you should use achors

 ^([1-9]{4}|[1-9]{6})$

here

 ^                   - beginning of the string
 ([1-9]{4}|[1-9]{6}) - either 4 or 6 digits 
 $                   - end of the string

You can wrap it into the method as

public static bool ValidatePIN(string pin) =>
  Regex.IsMatch(pin, @"^([1-9]{4}|[1-9]{6})$");

Another possibility is Linq:

public static bool ValidatePIN(string pin) =>
  pin != null &&
 (pin.Length == 4 || pin.Length == 6) &&
  pin.All(c => c >= '0' && c <= '9');

Upvotes: 2

Related Questions