Control Flow

Foreach Loops

A foreach loop visits each item in a collection.

foreach A foreach loop assigns each item to a loop variable for one pass through the block.

Foreach Loops

bonus
ForeachLoop.cs
Replay: real traced execution (multi-file project)
using System;

class Program
{
    static void Main()
    {
        int bonus = 1;
        int[] scores = { 2, 4, 6 };
        int total = 0;

        foreach (int score in scores)
        {
            total += score + bonus;
        }

        Console.WriteLine($"bonus={bonus}");
        Console.WriteLine($"total={total}");
    }
}

using System;

class Program
{
    static void Main()
    {
        int bonus = 0;
        int[] scores = { 2, 4, 6 };
        int total = 0;

        foreach (int score in scores)
        {
            total += score + bonus;
        }

        Console.WriteLine($"bonus={bonus}");
        Console.WriteLine($"total={total}");
    }
}

using System;

class Program
{
    static void Main()
    {
        int bonus = 3;
        int[] scores = { 2, 4, 6 };
        int total = 0;

        foreach (int score in scores)
        {
            total += score + bonus;
        }

        Console.WriteLine($"bonus={bonus}");
        Console.WriteLine($"total={total}");
    }
}

  1. bonus ← 1, total ← 0

    4{5    static void Main()6    {7        int bonus→ 1 = 1; //@bonus=0, 38        int[] scores = { 2, 4, 6 };9        int total→ 0 = 0;

  2. total ← 3

    pass 1 of 3
    11foreach (int score2 in scores)12{13    total→ 3 += score2 + bonus1;14}
    All 3 passes — pass 1 is the card above
    passscoretotal
    123
    248
    3615

  3. Console.WriteLine($"bonus={bonus}");

    16    Console.WriteLine($"bonus={bonus1}");17    Console.WriteLine($"total={total15}");18}
    outputbonus=1
total=15

  1. bonus ← 0, total ← 0

    4{5    static void Main()6    {7        int bonus→ 0 = 0;8        int[] scores = { 2, 4, 6 };9        int total→ 0 = 0;

  2. total ← 2

    pass 1 of 3
    11foreach (int score2 in scores)12{13    total→ 2 += score2 + bonus0;14}
    All 3 passes — pass 1 is the card above
    passscoretotal
    122
    246
    3612

  3. Console.WriteLine($"bonus={bonus}");

    16    Console.WriteLine($"bonus={bonus0}");17    Console.WriteLine($"total={total12}");18}
    outputbonus=0
total=12

  1. bonus ← 3, total ← 0

    4{5    static void Main()6    {7        int bonus→ 3 = 3;8        int[] scores = { 2, 4, 6 };9        int total→ 0 = 0;

  2. total ← 5

    pass 1 of 3
    11foreach (int score2 in scores)12{13    total→ 5 += score2 + bonus3;14}
    All 3 passes — pass 1 is the card above
    passscoretotal
    125
    2412
    3621

  3. Console.WriteLine($"bonus={bonus}");

    16    Console.WriteLine($"bonus={bonus3}");17    Console.WriteLine($"total={total21}");18}
    outputbonus=3
total=21

Add Each Score

  1. bonus starts at 1.
  2. The scores are 2, 4, and 6.
  3. Each pass adds the score plus the bonus.
  4. The final total is 15. | Score | Added with bonus 1 | Running total | | --- | --- | --- | | 2 | 3 | 3 | | 4 | 5 | 8 | | 6 | 7 | 15 |

Exercise: ForeachLoop.cs

Use foreach to add each score plus a bonus and print the total