Variable number of arguments

The params keyword is very handy when you don't know the number of arguments is variable.
Note! No additional parameters are permitted after the params keyword.

// This method can take a variable number of ints
public int Sum(params int[] values)
{
  int sum = 0;
  foreach(int value in values)
  {
    sum += value;
  }
  return sum;
}

// Method calls
int sum1 = Sum(1, 2, 3, 4);
int sum2 = Sum(1, 2);

But be aware that this comes with a performance cost. When this method is called an array must be created, which is a costly operation.

If you know that your code for most of the time is calling this method with 3 arguments, then make a override with only three arguments. This method call is much quicker.

// Override with three params
public int Sum(int val1, int val2, int val3) { /* ... */ }