CODE EXAMPLE FOR CSHARP

regex c# password numbers and letters

    private bool ValidatePassword(string password, out string ErrorMessage)
        {
            var input = password;
            ErrorMessage = string.Empty;

            if (string.IsNullOrWhiteSpace(input))
            {
                throw new Exception("Password should not be empty");
            }

            var hasNumber = new Regex(@"[0-9]+");
            var hasUpperChar = new Regex(@"[A-Z]+");
            var hasMiniMaxChars = new Regex(@".{8,15}");
            var hasLowerChar = new Regex(@"[a-z]+");
            var hasSymbols = new Regex(@"[!@#$%^&*()_+=[{]};:<>|./?,-]");

            if (!hasLowerChar.IsMatch(input))
            {
                ErrorMessage = "Password should contain at least one lower case letter.";
                return false;
            }
            else if (!hasUpperChar.IsMatch(input))
            {
                ErrorMessage = "Password should contain at least one upper case letter.";
                return false;
            }
            else if (!hasMiniMaxChars.IsMatch(input))
            {
                ErrorMessage = "Password should not be lesser than 8 or greater than 15 characters.";
                return false;
            }
            else if (!hasNumber.IsMatch(input))
            {
                ErrorMessage = "Password should contain at least one numeric value.";
                return false;
            }

            else if (!hasSymbols.IsMatch(input))
            {
                ErrorMessage = "Password should contain at least one special case character.";
                return false;
            }
            else
            {
                return true;
            }
        }