C# how to use enum with switch

Question

I can\'t figure out how to use switches in combination with an enum. Could you please tell me what I\'m doing wrong, and how to fix it? I have to use an enum to make a basic

Answer 1

Your code is fine. In case you're not sure how to use Calculate function, try

Calculate(5,5,(Operator)0); //this will add 5,5
Calculate(5,5,Operator.PLUS);// alternate

Default enum values start from 0 and increase by one for following elements, until you assign different values. Also you can do :

public enum Operator{PLUS=21,MINUS=345,MULTIPLY=98,DIVIDE=100};

Answer 2

Since C# 8.0 introduced a new switch expression for enums you can do it even more elegant:

public double Calculate(int left, int right, Operator op) =>
            op switch 
        {
            Operator.PLUS => left + right,
            Operator.MINUS => left - right,
            Operator.MULTIPLY => left * right,
            Operator.DIVIDE => left / right,
            _    =>  0
        }

Ref. https://docs.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-8

Answer 3

You should not cast to integer. And for the division, you need to cast left to double first, if not you will be doing an integer divide.

public enum Operator
{
    PLUS, MINUS, MULTIPLY, DIVIDE
}

public double Calculate(int left, int right, Operator op)
{
    double sum = 0.0;

    switch(op)
    {
       case Operator.PLUS:
       sum = left + right;
       return sum;

       case Operator.MINUS:
       sum = left - right;
       return sum;

       case Operator.MULTIPLY:
       sum = left * right;
       return sum;

       case Operator.DIVIDE:
       sum = (double)left / right;
       return sum;

       default:
       return sum;
   }

   return sum;
}

Answer 4

No need to convert. You can apply conditions on Enums inside a switch. Like so,

public enum Operator
{ 
    PLUS,
    MINUS,
    MULTIPLY,
    DIVIDE
}

public double Calculate(int left, int right, Operator op)
{
    switch (op)
    {
        case Operator.PLUS: return left + right; 
        case Operator.MINUS: return left - right; 
        case Operator.MULTIPLY: return left * right;
        case Operator.DIVIDE: return left / right;
        default: return 0.0; 
    }
}

Then, call it like this:

Console.WriteLine("The sum of 5 and 5 is " + Calculate(5, 5, Operator.PLUS));

Answer 5

In case you don't want to use return statement for each case, try this:

Calculate(int left, int right, Operator op)
{
   int result = 0;
   switch(op)
   {
        case Operator.PLUS:
        {
            result = left + right;;  
        }
        break;
        ....
   }

   return result;
}

Answer 6

All the other answers are correct, but you also need to call your method correctly:

Calculate(5, 5, Operator.PLUS))

And since you use int for left and right, the result will be int as well (3/2 will result in 1). you could cast to double before calculating the result or modify your parameters to accept double