How to detect uppercase in string ASP.NET

Question

I need to make a password validation where you can only register if your password contains an Uppercase and lowercase letters. But i can't find out how to detect if a letter is uppercase or lowercase. I Hope someone is able to help me with it :)

Here's my code till now! :

  if(!username.Contains("@nhl.nl")){
    errorMessage = "Voer een geldig NHL adres in.";
} 
else 
{
    if(DOESN'T CONTAIN UPPER CASE GIVE ERROR! ){
        errorMessage = "Het wachtwoord moet een hoofdletter bevatten!";
    }
    else {
    if(password.Length < 8){
        errorMessage = "Je wachtwoord moet minimaal 8 karakters bevatten!";
    }
    else {
        if(password != confirmPassword){
          errorMessage = "Wachtwoorden komen niet overeen!";
        }
        else {
          if(WebSecurity.UserExists(username)){
            errorMessage = String.Format("User '{0}' already exists.", username);
          }
          else{
            WebSecurity.CreateUserAndAccount(username,password,null,false);
            WebSecurity.Login(username, password, true);
            errorMessage = String.Format("{0} created.", username);
            }
          }
          }
      }
    }

@SainPradeep Yes it is, but how can i implement it into the if statement? — Leipelopo
– Leipelopo, Commented Mar 4, 2015 at 12:35

Sjoerd · Accepted Answer · 2017-05-03 09:18:46Z

3

Replace:

if(DOESN'T CONTAIN UPPER CASE GIVE ERROR! ){
    errorMessage = "Het wachtwoord moet een hoofdletter bevatten!";
}

With:

if(password.ToLower() == password){
    errorMessage = "Het wachtwoord moet een hoofdletter bevatten!";
}

If there is an upper case letter in it the two strings can never be the same.

edited May 3, 2017 at 9:18

answered Mar 4, 2015 at 12:36

Sjoerd

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1 Comment

Andrew Grothe Over a year ago

At first I was like, that doesn't answer the question at all... second glance, you sneaky coder you.

gabriel · Accepted Answer · 2015-03-04 12:46:21Z

1

if(!userName.Any(char.IsUpper)){
    errorMessage = "Het wachtwoord moet een hoofdletter bevatten!";
}

You'll need System.Linq

answered Mar 4, 2015 at 12:46

gabriel

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Comments

Arunprasanth K V · Accepted Answer · 2015-03-04 13:14:04Z

0

Sounds like in password is valid only when it contains a Uppercase character

then it is better to use LINQ

Eample :

string val = "aaabbb";
bool val1= val.Any(c => char.IsUpper(c));

val1 will be false here

string val = "aaabbbX";
bool val1= val.Any(c => char.IsUpper(c));

val1 will be true here

if you want to check string contains lower and upper case then

string val = "aaabbbX";
if (val.Any(char.IsUpper) && val.Any(char.IsLower))
{
// do your code here 
}

answered Mar 4, 2015 at 13:14

Arunprasanth K V

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Comments

Lightness Races in Orbit · Accepted Answer · 2015-03-25 17:05:27Z

0

Use this function to find if the Character is a Upper Case or Lower Case

using System;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string inputString = "Welcome !!!";
            foreach(char input in inputString)
            {
                if(Char.IsLower(input))
                    Console.WriteLine(input + " is a Lower Case Character");
                else if (Char.IsUpper(input))
                    Console.WriteLine(input + " is a upper Case Character");

            }

            Console.Read();
        }
    }
}

edited Mar 25, 2015 at 17:05

Lightness Races in Orbit

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answered Mar 4, 2015 at 12:43

Shanu Shaji

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