C# User input validation, if user enters Q at any console.ReadLine it will quit the program and i ca-CodePudding

using System;

namespace SummerWorkTask1
{
    class Program
    {
        static void Main(string[] args)
        {
            string firstName;
            string surname;
            string dateOfBirth;

            do
            {
                Console.WriteLine("Please enter your frist name and if at anytime you want to quit enter Q\n");
                firstName = Console.ReadLine().ToUpper();
                Console.WriteLine("Now enter your surname\n");
                surname = Console.ReadLine().ToUpper();
                Console.WriteLine("Lastly, enter your date of birth in the format of DD/MM/YY \n");
                dateOfBirth = Console.ReadLine().ToUpper();

                string customerID = $"{dateOfBirth.Replace("/", "")}{surname.Substring(0, 3)}{firstName.Substring(0, 1)}{firstName.Length} ";
                Console.WriteLine(customerID);
            } while (!firstName.Equals("Q") || !surname.Equals("Q") || !dateOfBirth.Equals("Q"));
        }
    }
}

CodePudding user response：

You need to check for Q as you go. Here's the way I would look at it if I were you.

static void Main(string[] args)
{
    string Ask(string message)
    {
        Console.WriteLine(message);
        string input = Console.ReadLine().ToUpper();
        Console.WriteLine();
        return input;
    }

    while (true)
    {
        string firstName = Ask("Please enter your first name and if at anytime you want to quit enter Q");
        if (firstName.Equals("Q"))
            break;
        else
        {
            string surname = Ask("Now enter your surname");
            if (surname.Equals("Q"))
                break;
            else
            {
                string dateOfBirth = Ask("Lastly, enter your date of birth in the format of DD/MM/YY");
                if (dateOfBirth.Equals("Q"))
                    break;
                else
                {
                    string customerID = $"{dateOfBirth.Replace("/", "")}{surname.Substring(0, 3)}{firstName.Substring(0, 1)}{firstName.Length} ";
                    Console.WriteLine(customerID);
                }
            }
        }
    }
}

I'd recommend against using the Environment.Exit(0); option as this only allows you one outcome. There will be few occasions in writing larger programs where you'll actually want to quit like this.

CodePudding user response：

The problem is that the condition you enter in the while() is executing only at the end of the loop and it happend after the CustomerID initiation. Also the fact that you exit the loop is not the right way to close the program.

try this maybe it will help:

 static void Main(string[] args)
        {
            string firstName;
            string surname;
            string dateOfBirth;
            
            while (true)
            {
                Console.WriteLine("Please enter your frist name and if at anytime you want to quit enter Q\n");
                firstName = Console.ReadLine().ToUpper();
                CheckForQ(firstName); //check if user enter q
                Console.WriteLine("Now enter your surname\n");
                surname = Console.ReadLine().ToUpper();
                CheckForQ(surname); //check if user enter q
                Console.WriteLine("Lastly, enter your date of birth in the format of DD/MM/YY \n");
                dateOfBirth = Console.ReadLine().ToUpper();
                CheckForQ(dateOfBirth); //check if user enter q
                string customerID = $"{dateOfBirth.Replace("/", "")}{surname.Substring(0, 3)}{firstName.Substring(0, 1)}{firstName.Length} ";
                Console.WriteLine(customerID);
            }
        }

        private static void CheckForQ(string line)
        {
            if (line.Equals("Q"))
            {
                Environment.Exit(0);
            }
        }