Using a switch statement

Unity Courses Talk
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#1

I found this exercise easier to solve using a switch statement rather than if else. Here is my code for ActionMaster.cs (refactored) it seems to pass all the tests:

Would there be any downside to using this technique instead?

using UnityEngine;
using System.Linq;

public class ActionMaster
{
public enum Action { Tidy, Reset, EndTurn, EndGame };

private int[] _bowlScores = Enumerable.Repeat(0, 21).ToArray(); // 21 elements initilised to 0
private int   _currentBowl = 1;

public Action Bowl (int pins)
{
    // Guard
    if (pins < 0 || pins > 10) throw new UnityException("Can not accept more than 10 or less than 0 pins in ActionMaster.Bowl()");

    // Record pins down for current bowl
    _bowlScores[_currentBowl - 1] = pins;

    // Last frame special cases
    //
    //  [19]             [20]            [21]
    //   0  - tidy        0  - end        
    //   5  - tidy        1  - end
    //   5  - tidy        5  - reset      x
    //   10 - reset       0  - tidy       x
    //   10 - reset       5  - tidy       x
    //   10 - reset       10 - reset      x

    switch(_currentBowl)
    {
        case 19:
            _currentBowl++;

            if (pins != 10) return Action.Tidy;
            else return Action.Reset;

        case 20:
            _currentBowl++;

            var previousScore = _bowlScores[19 - 1];

            if (previousScore != 10 && previousScore + pins != 10) return Action.EndGame;
            if (previousScore != 10 && previousScore + pins == 10) return Action.Reset;
            if (previousScore == 10 && pins != 10) return Action.Tidy;
            else return Action.Reset;

        case 21:
            return Action.EndGame;
    }

    // Otherwise if you bowl a stike you end the turn and increment the current bowl by 2
    if (pins == 10)
    {
        _currentBowl += 2;
        return Action.EndTurn;
    }

    // All other cases need the current bowl incremented by 1 after the conditional test
    // Tidy if odd number tidy, other wise end turn
    if (_currentBowl++ % 2 != 0) return Action.Tidy;
    else return Action.EndTurn;

    // Failed to resolve
    throw new UnityException("No Action.type returned from ActionMaster.Bowl()");
}

}

#2

I like this solution, but just wondering if the table set out in comments it something that you just used for reference or whether it is needed in the code (I assume just fro reference). But i love the Switch method. Easier to read that Ben’s

#3

Hi Darkokubra,

Yes, table is just for reference.

1 Like
#4

Nice to see that I wasn’t the only one who relied on a Switch statement instead of multiple IFs.

My code is as follows:

[code]using System.Linq;
using UnityEngine;

public class BowlController {

public enum AfterBowl {Tidy, EndFrame, EndGame};

private int[] bowlShot = Enumerable.Repeat(0,22).ToArray();
private int bowlIndex = 1;

public AfterBowl BowlEndAction(int pins){
    if (pins < 0 || pins > 10) {throw new UnityException ("Number of Pins out of range 0-10");}

    bowlShot[bowlIndex-1] = pins;
    bowlIndex++;

    switch (bowlIndex){

        case 23: //2nd bonus throw after 10th frame strike
        return AfterBowl.EndGame;

        case 22: //1st bonus throw after 10th frame strike/spare
        if (bowlShot[18] == 10) return AfterBowl.Tidy;
        else return AfterBowl.EndGame;

        case 21: //10th frame spare check
        if (bowlShot[18] + bowlShot[19] == 10) return AfterBowl.EndFrame;
        else return AfterBowl.EndGame;

        default:
        if ( (bowlIndex-1) %2 == 0) return AfterBowl.EndFrame;
        else {
            if (pins == 10) {
                bowlIndex++;
                return AfterBowl.EndFrame;
            } else return AfterBowl.Tidy;
        }
    }
}

}
[/code]

I tried to minimize the number of instructions to execute, I guess that less than this it’s impossible to go, but I’d love to be proven wrong. :smiley:

P.S.: In my algorithm the two bonus throws after the 10th frame are handled like a new frame (i.e.: index 21 and 22), which removes some more checks on shot 20 as a part of a 19th strike.

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