为什么我的c＃程序返回0？

Question

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

namespace Fahrenheit_to_Celsius_Converter
{
    class Program
    {
        static void Main(string[] args)
        {//Prompt user to enter a temperature
            Console.WriteLine("Please enter the temperature in fahrenheit you want to convert");
            //Sets variable fahr to the number entered
            string fahr = Console.ReadLine();
            //Just for testing debugging purposes displays what data is stored in fahr.
            Console.WriteLine(fahr);
            //Initializes an integer fahrint
            int fahrint;
            fahrint = int.Parse(fahr);
            //Just for testing debugging purposes displays what data is stored in fahrint.
            Console.WriteLine(fahrint);
            //Initializes an integer celcius
            decimal celcius;
            //Does the calculation that stores to a variable called celcius
            celcius = ((fahrint) - 32) * (5 / 9);
            //At this point the celcius variable print 0. It should print 5 if 41 is entered
            Console.WriteLine(celcius);
            string celciusstring;
            celciusstring = celcius.ToString();
            Console.WriteLine(celciusstring);



        }
    }
}

I have commented on what is happening in my code as much as possible. The program stores Fahrenheit as a string and converts it to a decimal fine. However, celcius = 0 instead of the correct number at the point where celcius = celcius = ((fahrint) - 32) * (5 / 9);. I am aware I spelt celcius wrong, but I do not believe it hase effected the code. Any solutions?

Thanks!

Answer 1

Integer Division. 5 / 9 is always 0

(fahrint - 32) * (5 / 9)
                   ^^^  

You need to cast at least one of those values to a decimal :

celcius = (fahrint - 32) * (5M / 9);
//5 is of type Decimal now

Answer 2

All literal numbers are of type integer by default. When doing integer division, the result is "rounded" down to the nearest whole number, in this case 0 . So the result is always 0.

You need to declare one of those as a decimal to force it to not perform integer division using m :

celcius = ((fahrint) - 32) * (5m / 9); //5 is now a decimal