C# Console Application Password Input Checker

Question

The following code has preset passwords that the user must enter to continue the code. However, when the set passwords (PASS1-PASS3) are entered, the code goes to the do-while regardless. What do I need to do in order to make the while recognize that the password is correct so that it does not go to the invalid password line?

// Program asks user to enter password
// If password is not "home", "lady" or "mouse"
// the user must re-enter the password
using System;
public class DebugFour1
{
public static void Main(String[] args)
  {
const String PASS1 = "home";
const String PASS2 = "lady";
const String PASS3 = "mouse";
String password;
String Password;
Console.Write("Please enter your password ");
password = Console.ReadLine();
do
{
    Console.WriteLine("Invalid password enter again: ");
    password = Console.ReadLine();
} while (password != PASS1 || password != PASS2 || password != PASS3);
Console.WriteLine("Valid password");
Console.ReadKey();

 }
}

Answer 1

You have your logic the wrong way around i.e. do something then check some conditions, whereas you want to check some conditions and then do something. So the following code:

do
{
    Console.WriteLine("Invalid password enter again: ");
    password = Console.ReadLine();
} while (password != PASS1 || password != PASS2 || password != PASS3);

Should read:

while (password != PASS1 && password != PASS2 && password != PASS3)
{
    Console.WriteLine("Invalid password enter again: ");
    password = Console.ReadLine();
} 

Notice that I also changed the logical ORs || to logical ANDs &&. this is because you want to check if it is not equal to all of them, not just one.

On a side note the variable Password is unused and should be removed as it can lead to typo errors to your used variable password.