Summary - Method parameters

C# course · Beginner · Lesson 82/116

Combine default, params, ref and out to write a calculation method.

Summary - Method parameters

In this section you learned the default, params, ref and out parameter kinds. Default adds flexibility at the call, params takes a variable number of arguments, ref changes by reference, and out returns multiple values.

Now we will combine them into a small calculation method. Summation with params and a divide that returns both quotient and remainder via out will come together.

Exercise Sum five numbers with params

Define a static int Sum(params int[] nums) method; sum with foreach and return the result. In Main, call Sum(1, 2, 3, 4, 5) and print the result with Console.WriteLine.

Show example solution

Add int total = 0; foreach (int n in nums) total += n; return total; to the Sum body, write Console.WriteLine(Sum(1, 2, 3, 4, 5)); in Main.
Example solution:
using System;

class Program
{
    static int Sum(params int[] nums)
    {
        // Sum with foreach
        int total = 0;
        foreach (int n in nums) total += n;
        return total;
    }

    static void Main()
    {
        // Call Sum and print
        Console.WriteLine(Sum(1, 2, 3, 4, 5));
    }
}

Exercise Divide with out

Define static void Divide(int a, int b, out int q, out int r); in the body assign q = a / b; and r = a % b;. In Main, call Divide(20, 6, out int q, out int r) and print q with Console.WriteLine.

Show example solution

Add q = a / b; and r = a % b; to the Divide body, write Divide(20, 6, out int q, out int r); Console.WriteLine(q); in Main.
Example solution:
using System;

class Program
{
    static void Divide(int a, int b, out int q, out int r)
    {
        // Assign q and r
        q = a / b;
        r = a % b;
    }

    static void Main()
    {
        // Call Divide and print q
        Divide(20, 6, out int q, out int r);
        Console.WriteLine(q);
    }
}

Test yourself

Match the concepts

default

Default value
params

Variable args
ref

By reference
out

Output parameter
What does Console print after Double(ref x)?
```
static void Double(ref int n) { n *= 2; }
int x = 5;
Double(ref x);
Console.WriteLine(x);
```
- 10
- 5
- 20
- 0
Show answer

10 — Correct. With ref, x itself was changed; x = 10.

ref call

int x = 4;
Double(____);
Console.WriteLine(x);

Show answer

int x = 4;
Double(ref x);
Console.WriteLine(x);

Summary - Method parameters