Control Flow

Break and Continue

break stops a loop, while continue skips to the next loop step.

loop control Loop control statements change how a loop proceeds.

Break and Continue

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

class Program
{
    static void Main()
    {
        int stopAt = 5;
        int kept = 0;
        int seen = 0;

        for (int value = 1; value <= 7; value++)
        {
            if (value > stopAt)
            {
                break;
            }
            if (value % 2 == 0)
            {
                continue;
            }
            kept += value;
            seen++;
        }

        Console.WriteLine($"stopAt={stopAt}");
        Console.WriteLine($"seen={seen}");
        Console.WriteLine($"kept={kept}");
    }
}

using System;

class Program
{
    static void Main()
    {
        int stopAt = 3;
        int kept = 0;
        int seen = 0;

        for (int value = 1; value <= 7; value++)
        {
            if (value > stopAt)
            {
                break;
            }
            if (value % 2 == 0)
            {
                continue;
            }
            kept += value;
            seen++;
        }

        Console.WriteLine($"stopAt={stopAt}");
        Console.WriteLine($"seen={seen}");
        Console.WriteLine($"kept={kept}");
    }
}

using System;

class Program
{
    static void Main()
    {
        int stopAt = 7;
        int kept = 0;
        int seen = 0;

        for (int value = 1; value <= 7; value++)
        {
            if (value > stopAt)
            {
                break;
            }
            if (value % 2 == 0)
            {
                continue;
            }
            kept += value;
            seen++;
        }

        Console.WriteLine($"stopAt={stopAt}");
        Console.WriteLine($"seen={seen}");
        Console.WriteLine($"kept={kept}");
    }
}

  1. stopAt ← 5, kept ← 0, seen ← 0

    4{5    static void Main()6    {7        int stopAt→ 5 = 5; //@stopAt=3, 78        int kept→ 0 = 0;9        int seen→ 0 = 0;

  2. kept ← 1, seen ← 1

    pass 1 of 6
    11for (int value1 = 1; value <= 7; value++)12{13    if (value > stopAt)14    {15        break;16    }17    if (value % 2 == 0)18    {19        continue;20    }21    kept→ 1 += value1;22    seen→ 1++;23}
    All 6 passes — pass 1 is the card above
    passvaluestopAtkeptseen
    11—10 → 1
    22———
    33—41 → 2
    44———
    55—92 → 3
    665——

  3. if (value % 2 == 0)

    pass 1 of 2
    16}17if (value2 % 2 == 0)18{19    continue;20}

  4. if (value % 2 == 0)

    pass 2 of 2
    16}17if (value4 % 2 == 0)18{19    continue;20}

  5. if (value > stopAt)

    12{13    if (value6 > stopAt5)14    {15        break;16    }

  6. Console.WriteLine($"stopAt={stopAt}");

    25    Console.WriteLine($"stopAt={stopAt5}");26    Console.WriteLine($"seen={seen3}");27    Console.WriteLine($"kept={kept9}");28}
    outputstopAt=5
seen=3
kept=9

  1. stopAt ← 3, kept ← 0, seen ← 0

    4{5    static void Main()6    {7        int stopAt→ 3 = 3;8        int kept→ 0 = 0;9        int seen→ 0 = 0;

  2. kept ← 1, seen ← 1

    pass 1 of 4
    11for (int value1 = 1; value <= 7; value++)12{13    if (value > stopAt)14    {15        break;16    }17    if (value % 2 == 0)18    {19        continue;20    }21    kept→ 1 += value1;22    seen→ 1++;23}
    All 4 passes — pass 1 is the card above
    passvaluestopAtkeptseen
    11—10 → 1
    22———
    33—41 → 2
    443——

  3. if (value % 2 == 0)

    16}17if (value2 % 2 == 0)18{19    continue;20}

  4. if (value > stopAt)

    12{13    if (value4 > stopAt3)14    {15        break;16    }

  5. Console.WriteLine($"stopAt={stopAt}");

    25    Console.WriteLine($"stopAt={stopAt3}");26    Console.WriteLine($"seen={seen2}");27    Console.WriteLine($"kept={kept4}");28}
    outputstopAt=3
seen=2
kept=4

  1. stopAt ← 7, kept ← 0, seen ← 0

    4{5    static void Main()6    {7        int stopAt→ 7 = 7;8        int kept→ 0 = 0;9        int seen→ 0 = 0;

  2. kept ← 1, seen ← 1

    pass 1 of 7
    11for (int value1 = 1; value <= 7; value++)12{13    if (value > stopAt)14    {15        break;16    }17    if (value % 2 == 0)18    {19        continue;20    }21    kept→ 1 += value1;22    seen→ 1++;23}
    All 7 passes — pass 1 is the card above
    passvaluekeptseen
    1110 → 1
    22——
    3341 → 2
    44——
    5592 → 3
    66——
    77163 → 4

  3. if (value % 2 == 0)

    pass 1 of 3
    16}17if (value2 % 2 == 0)18{19    continue;20}
    All 3 passes — pass 1 is the card above
    passvalue
    12
    24
    36

  4. Console.WriteLine($"stopAt={stopAt}");

    25    Console.WriteLine($"stopAt={stopAt7}");26    Console.WriteLine($"seen={seen4}");27    Console.WriteLine($"kept={kept16}");28}
    outputstopAt=7
seen=4
kept=16

Keep Odd Values Until Stop

  1. stopAt starts at 5.
  2. The loop checks values from 1 through 7.
  3. Even values use continue, so they are skipped.
  4. Values above 5 use break, so the loop stops.
  5. The kept total is 1 + 3 + 5, which is 9. | Value | Action | Seen | Kept | | --- | --- | --- | --- | | 1 | add | 1 | 1 | | 2 | continue | 1 | 1 | | 3 | add | 2 | 4 | | 4 | continue | 2 | 4 | | 5 | add | 3 | 9 | | 6 | break | 3 | 9 |

Exercise: BreakContinue.cs

Use continue to skip even values, break after a stop value, and print seen and kept totals