更有效的输入检查方式？

Question

New programmer here! I'm just wondering if there is a more efficient way of checking the input in the code below?

I use a while loop in combination with TryParse to see if the input is valid. As you can see, I'm reusing the code. I would like to do something similar with the first user input as well. Basically it's a piece of code that I will be able to re-use many times in a program.

Is there any way to make this more efficient without re-writing the code all the time? Could this be implemented in a function of sorts?

namespace Calculator2
{
    class GetUserInput
    {
        public char MethodChoice;
        private string _numberOne;
        private string _numberTwo;
        public int NumberOne;
        public int NumberTwo;

        public void GetCalculationMethod()
        {
            Console.WriteLine("Welcome to calculator v.2!");
            Console.WriteLine("Please choose a method of calculation!");
            Console.WriteLine("1: Addition");
            Console.WriteLine("2: Subtraction");
            Console.Write("Your choice: ");
            MethodChoice = Console.ReadKey().KeyChar;
        }

        public void GetCalculationNumbers()
        {
            Console.Clear();
            Console.WriteLine("Please enter two numbers...");
            while (!int.TryParse(_numberOne, out NumberOne))
            {
                _numberOne = Console.ReadLine();

                if (!int.TryParse(_numberOne, out NumberTwo))
                {
                    Console.WriteLine("Invalid input, try again!");
                }
            }

            Console.WriteLine("Number two: ");
            while (!int.TryParse(_numberTwo, out NumberTwo))
            {
                _numberTwo = Console.ReadLine();

                if (!int.TryParse(_numberTwo, out NumberTwo))
                {
                    Console.WriteLine("Invalid input, try again!");
                }
            }
        }
    }
}

Answer 1

Your code doesn't seem quite right. It never reads the user's input until after TryParse() fails. Also, it's a red flag to call TryParse() twice for the same input.

At any rate, the most obvious way to eliminate repeated code is to move the repeated code into a separate method, and then just call that method.

For example:

int GetInteger(string prompt)
{
    Console.WriteLine(prompt);
    while (true)
    {
        string s = Console.ReadLine();
        int value;
        if (int.TryParse(s, out value))
            return value;
        Console.WriteLine("Invalid input, try again!");
    }
}

And then use it like this:

public void GetCalculationNumbers()
{
    Console.Clear();
    NumberOne = GetInteger("Please enter two numbers...");
    NumberTwo = GetInteger("Number two: ");
}

Note that you should add a way for the user to cancel, in case they don't want to complete the input.