Question

So I have a function

public int Sum(var valueA, var valueB, var valueC) { 
  var summ = valueA + valueB; 
  return summ; 
} 

I want to add to summ valueC if it was given. And let user not specify it if he does not want to. How to do such thing?

Answer 1

In addition to the options that Shane Fulmer provided, you can also use the params keyword to have a function that takes a variable number of parameters:

public int Sum(params int[] values)
{
    int sum = 0;
    for(int i = 0; i < values.Length; i++){
        sum+=values[i];
    }
    return sum;
}

int answer2Parameters = Sum(1, 5);
int answer3Parameters = Sum(1, 2, 3);
int answer4Parameters = Sum(1, 3, 5, 6);

Of course if you want to limit them to exactly two or three then you probably want to look at optional parameters in C#4.0 or overload the Sum function – by this I mean create two Sum functions, one that takes two parameters and another that takes 3 parameters.

public int Sum(int valueA, int valueB) { 
  int summ = valueA + valueB; 
  return summ; 
} 

public int Sum(int valueA, int valueB, int valueC) { 
  int summ = valueA + valueB + valueC; 
  return summ; 
}