Validating password using regex c# [duplicate]

Question

This must be simple and I expect it working in the same way but it's not helping me out.

using System;
using System.Text.RegularExpressions;

I am in a need of password validation regular expression with certain conditions where -

1) It must contain at least a number

2) one upper case letter

3) 8 characters long.

public class Program
{
     public static bool IsValidPassword(string plainText) {
            Regex regex = new Regex(@"^(.{0,7}|[^0-9]*|[^A-Z])$");
            Match match = regex.Match(plainText);
            return match.Success;
}
    public static void Main()
    {
        Console.WriteLine(IsValidPassword("shing"));    //logs 'True' always
    }
}

I've taken regex from this source- Password must be 8 characters including 1 uppercase letter, 1 special character, alphanumeric characters

Issue is that it returns 'True' always and the string that I am sending to method is not valid.

Help me if I am doing something wrong with the regex.

Please play with it here- https://dotnetfiddle.net/lEFYGJ

Answer 1

I recommend you create separate patterns to validate the password:

var input = "P@ssw0rd";

var hasNumber = new Regex(@"[0-9]+");
var hasUpperChar = new Regex(@"[A-Z]+");
var hasMinimum8Chars = new Regex(@".{8,}");

var isValidated = hasNumber.IsMatch(input) && hasUpperChar.IsMatch(input) && hasMinimum8Chars.IsMatch(input);
Console.WriteLine(isValidated);