C# calculator user input issue

Question

I am trying to create a C# calculator for a class, but when I try to use it it always returns blatantly wrong answers, like 1+3 = 100, or rounding down the decimal 2.33 to 50. It also crashes after the first input every time, which makes me think that its reading when i press enter for some reason, but I've looked and can't find documentation on any issue like that. Thanks in advance.

'

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace calculator
{
    class Program
    {
        static void Main(string[] args)
        {
            //set label for finished functions to return to
            start:
            System.Console.WriteLine("choose from one of the following calculator choices");
            System.Console.WriteLine("1: whole number");
            System.Console.WriteLine("2: addition");
            System.Console.WriteLine("3: sine");
            System.Console.WriteLine("4: cosine");
            System.Console.WriteLine("5: absolue value");
            System.Console.WriteLine("6: quit");
            int optionSelect = Convert.ToInt32(Console.ReadLine());
            
            switch (optionSelect)
            {
                
                case 1:
                    System.Console.WriteLine("whole number");
                    System.Console.WriteLine("give a decimal");
                    decimal temp = System.Console.Read();
                    System.Console.WriteLine(Convert.ToInt32(temp));
                    goto start;
                case 2:
                    System.Console.WriteLine("addition");
                    System.Console.WriteLine("first int");
                    int add1 = Convert.ToInt32(System.Console.ReadKey());
                    System.Console.WriteLine("second int");
                    Console.ReadLine();
                    int add2 = Convert.ToInt32(System.Console.Read());
                    Console.ReadLine();
                    int answer = add1+add2;
                    System.Console.WriteLine("the answer is " + answer);
                    goto start;
                case 3:
                    System.Console.WriteLine("sine");
                    System.Console.WriteLine("enter your angle in radians");
                    double numSin = Console.Read();
                    System.Console.WriteLine(Math.Sin(numSin));
                    goto start;
                case 4:
                    System.Console.WriteLine("cosine");
                    System.Console.WriteLine("enter your angle in radians");
                    double numCos = Console.Read();
                    System.Console.WriteLine(Math.Cos(numCos));
                    goto start;
                case 5:
                    System.Console.WriteLine("absolute value");
                    System.Console.WriteLine("enter a number");
                    double num = Convert.ToDouble(Console.Read());
                    System.Console.WriteLine(Math.Abs(num));
                    goto start;
                case 6:
                    System.Console.WriteLine("shutting down...");
                    goto start;
                default:
                    System.Console.WriteLine("invalid input");
                    goto start;

            }
            
            
            
        }
    }
}
`

Answer 1

So there are multiple problems in your code.

Console.Read will return the corresponding ASCII code for the first character that you enter. Here is a link with the ASCII table: http://www.asciitable.com/

So if you put in the console 0 is not actually 0 but the corespondent value for 0 in the ASCII table. 0=48, 1=49, 2=50 ... 9 = 50.

If you put multiple characters only the first one will be processed by Console.Read .

To fix your problem you could use as you did in the begging :

string line = Console.ReadLine();

and after that, you can convert that line to whatever you need like decimal x = Convert.ToDecimal(line) . or int x = Convert.ToInt32(line)

Also please try to change that goto logic into a while .