C#, How to return a string and Int from the same method

Question

How do I return a string from a Int method? Please see my code below. In the last method I would like to print the string "Invalid Operator" if the use keyed in a wrong operator

    static void Main(string[] args)
    {
        Console.WriteLine("Welcome to the simple calculator");
        Console.WriteLine("-------------");
        Console.WriteLine("Enter the first number");
        int num1 = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("Enter the Second number");
        int num2 = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("Select the Operator");
        Console.WriteLine("Key in on of the following numbers:\n" + "1 to add \n" + "2 to subtract \n" + "3 to multiply \n" + "4 to divide");
        int op = Convert.ToInt32(Console.ReadLine());
        Console.WriteLine("Your result is");
        Console.WriteLine("---------------");
        Console.WriteLine(GetResult(num1, num2, op));

        Console.ReadLine();
    }

I would like the below method to return both the String and Int values

static int GetResult(int a, int b, int c)
{
    int result;

    if (c == 1)
    {
        result = a + b;
    }
    else if (c == 2)
    {
        result = a - b;
    }
    else if (c == 3)
    {
        result = a * b;
    }
    else if (c == 4)
    {
        result = a / b;
    }
    else
    {
        result = "Invalid Operator"; 
    } 

    return result;
}

In this scenario I'd make the method signature static string GetResult(int a, int b, int c, out rersult). Then you could print your string result while also getting the numerical value. Although the use case doesn't make sense, hopefully there's a bigger purpose. — Yuriy Faktorovich
– Yuriy Faktorovich, Commented Oct 8, 2022 at 10:28
I think what you are actually looking for is the concept of exceptions, since you want to return an int value if the passed operator is expected and throw an exception of "invalid operator" if it is not. — hyt
– hyt, Commented Oct 8, 2022 at 10:34
@YuriyFaktorovich I added that, but I am getting an error > static int GetResult(int a, int b, int c, out result) { int result; if (c == 1) { result = a + b; } else if (c == 2) { result = a - b; } else if (c == 3) { result = a * b; }else if (c==4) { result = a / b; } else { result = "Invalid Operator"; } return result; } — Mtm
– Mtm, Commented Oct 8, 2022 at 10:39

Giles · Accepted Answer · 2022-10-08 10:51:25Z

5

You could use tuples, but I think an exception would be better here, e.g.

static int GetResult(int operatorCode, int operand1, int operand2) =>
    operatorCode switch
    {
        1 => operand1 + operand2,
        2 => operand1 - operand2,
        3 => operand1 * operand2,
        4 => operand1 / operand2,
        _ => throw new ArgumentOutOfRangeException(nameof(operatorCode), $"operatorCode {operatorCode} is not valid.")
    };

edited Oct 8, 2022 at 10:51

answered Oct 8, 2022 at 10:39

Giles

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1 Comment

Matthew Watson Over a year ago

In this case I'd use throw new ArgumentOutOfRangeException(nameof(operatorCode), $"operatorCode {operatorCode} is not valid."); since the error is indeed caused by an out-of-range argument.

Julian · Accepted Answer · 2022-10-08 11:03:11Z

I would recommend exceptions to handle invalid input.

However, you could also do one of these things:

Option 1: Value Tuple

static (int?, string) GetResult(int a, int b, int c)
{
    int? result = null;
    string error = null;

    if (c == 1)
    {
        result = a + b;
    }
    else if (c == 2)
    {
        result = a - b;

    }
    else if (c == 3)
    {
        result = a * b;
    }
    else if (c == 4)
    {
        result = a / b;
    }
    else
    {
        error = "Invalid operator";
    }

    return (result, error);
}

Option 2: Enum

public enum OperatorCode
{
   Add,
   Sub,
   Mul,
   Div
}

static int GetResult(OperatorCode operatorCode, int operand1, int operand2) =>
    operatorCode switch
    {
        OperatorCode.Add => operand1 + operand2,
        OperatorCode.Sub => operand1 - operand2,
        OperatorCode.Mul => operand1 * operand2,
        OperatorCode.Div => operand1 / operand2,
    };

This second option doesn't require an error message, because only valid operator codes can be passed to the method.

sascha · Accepted Answer · 2022-10-08 11:07:41Z

You can try this

'''

using System;

namespace example 
{
    public static class Program
        {
            static void Main(string[] args)
                {
                    Console.WriteLine("Welcome to the simple calculator");
                    Console.WriteLine("-------------");
                    Console.WriteLine("Enter the first number");
                    int num1 = Convert.ToInt32(Console.ReadLine());;
                    Console.WriteLine("Enter the Second number");
                    int num2 = Convert.ToInt32(Console.ReadLine());;
                    Console.WriteLine("Select the Operator");
                    Console.WriteLine("Key in on of the following numbers:\n" + "1 to add \n" + "2 to subtract \n" + "3 to multiply \n" + "4 to divide");
                    int op = Convert.ToInt32(Console.ReadLine());;
                    GetResult(num1, num2, op);
                }
            static void Invalid()
                {
                    Console.WriteLine("Invalid Operator, Try Again");
    
                }

            static void GetResult(int a, int b, int c)
                {
                    int result;
                    string pref = "Your result is: ";
                        if (c == 1)
                            {
                                result = a + b;
                                Console.WriteLine(pref+result);
                            }
                        else if (c == 2)
                            {
                                result = a - b;
                                Console.WriteLine(pref+result);
                            }
                        else if (c == 3)
                            {
                                result = a * b;
                                Console.WriteLine(pref+result);
                            }
                        else if (c==4)
                            {
                                result = a / b;
                                Console.WriteLine(pref+result);
                            }
                        else
                            {
                                Invalid(); 
                            } 
                }
        }
}

bini nebro · Accepted Answer · 2022-10-08 10:48:09Z

-1

You could change the return type from int to object

static object  GetResult(int a, int b, int c)
{
    object result;
    if (c == 1)
    {
        result = a + b;
    }
    else if (c == 2)
    {
        result = a - b;

    }
    else if (c == 3)
    {
        result = a * b;
    }
    else if (c == 4)
    {
        result = a / b;
    }
    else
    {
        result = "Invalid Operator";
    }
    return result;
}

I have never used objects for big projects. It is better to know the return type.

Or you could print while doing the operation. make the method void.

 Console.WriteLine(a +b);

answered Oct 8, 2022 at 10:48

bini nebro

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