How to loop back to the beginning of a switch statement after a case

Question

I have what I'm sure is a simple problem, but I can't figure it out. In the code below, I'd like to be able to have case 5 re-display the options afterward. How can I do this? Thanks in advance!

// Input the race of your character
    cout << "Choose a race here: " << endl
    << "1) Human, 2) Elf, 3) Dark Dwarf, 4) Commoner, 5) Race info, 6) Admin Debug Race : ";

    cin >> mCharRace;

    switch (mCharRace)
        {
        case 1:
        cout << "You have chosen Human!" << endl;
        mExpPoints = 999;
        mArmor = mArmor + 2;
        break;
    case 2:
        cout << "You have chosen Elf!" << endl;
        mAccuracy = mAccuracy + 2;
        mWeapon.mDamageRange.mLow = mWeapon.mDamageRange.mLow + 1;
        break;
    case 3:
        cout << "You have chosen Dark Dwarf!" << endl;
        mWeapon.mDamageRange.mHigh = mWeapon.mDamageRange.mHigh + 2;
        mMaxHitPoints = mMaxHitPoints + 3;
        break;
    case 4:
        cout << "You have chosen Commoner! Brave man." << endl;
        mAccuracy       = mAccuracy - 3;
        mHitPoints      = mHitPoints - 5;
        mMaxHitPoints   = 8;
        mExpPoints      = -250;
        mNextLevelExp   = 1500;
        mArmor          = -1;
        break;
    case 5:
        cout << "Placeholder for explanation text." << endl;
        break;
    case 6:
        cout << "ADMIN POWERS UNITE!!!!!!!" << endl;
        mAccuracy       = 20;
        mHitPoints      = 1000;
        mMaxHitPoints   = 1000;
        mExpPoints      = 0;
        mNextLevelExp   = 1000;
        mArmor          = 100;
        mWeapon.mName   = "Admin Sword of HNNNG!";
        mWeapon.mDamageRange.mLow   = 100;
        mWeapon.mDamageRange.mHigh  = 150;
        mGold           = 1000000;
        break;

Not an answer, 'cause I don't want to get hammered. There's always Duff's device: http://en.wikipedia.org/wiki/Duff's_device . — David Hammen, Oct 26 '12 at 15:27

score 12 · Accepted Answer · answered Oct 26 '12 at 15:00

A switch-case construct isn't an iteration construct. It can only select a certain case and execute it. The flow of control cannot go back up due to it.

So, you can't use it to loop. Wrap it in a while or for looping construct instead.

while(condition){
   switch (mCharRace){
   ...
   ...
   }
}

Just turn condition to false when you want to stop looping.

score 6 · Answer 2 · answered Oct 26 '12 at 15:00

6

Wrap the input and switch code in a loop, and assign a variable exitLoop to exit the loop. Set that variable to TRUE by default, except in those cases where you want to repeat the input. In those, set exitLoop to false.

answered Oct 26 '12 at 15:00

LSerni

55,617
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cjamesm · Answer 3 · 2012-10-26T15:01:03.367

1

Add a label before your first cout

label:

cout << "Choose a race here: " << endl
<< "1) Human, 2) Elf, 3) Dark Dwarf, 4) Commoner, 5) Race info, 6) Admin Debug Race : ";

cin >> mCharRace;
...

then inside the case 5, add

goto label;

edited Oct 26 '12 at 15:01

answered Oct 26 '12 at 15:00

cjamesm

109
7

Can I ask why this was downvoted? It works, and is simple. Is it just bad technique? – Vladimir Marenus Oct 26 '12 at 15:03
1

You will certainly love assembler, cjamesm :-) In all other cases, **please don't use a goto** (I didn't downvote) – John Dvorak Oct 26 '12 at 15:04
1

`goto` should be avoided in general in C++. There are uses for it, but this one doesn't really fit. – Mat Oct 26 '12 at 15:05
May I ask why, Mat? I'm probably getting over my head here, but I'm curious because it seems so elegant. – Vladimir Marenus Oct 26 '12 at 15:06
@Mat goto is never neccessary and seldom useful. Please provide an example where adding a goto helps readability. – John Dvorak Oct 26 '12 at 15:07
1

@Jan: that's an age-old debate I won't go into. I'll stick with exactly what I said: there are uses for it, but should be avoided in general. – Mat Oct 26 '12 at 15:08
Okay, anyone- why all the goto hate? Now I'm interested! :) – Vladimir Marenus Oct 26 '12 at 15:08
1

@Vladimir: some discussion here http://stackoverflow.com/questions/379172/to-use-goto-or-not – Mat Oct 26 '12 at 15:09
2

Thanks for the tips on goto, guys. I didn't know it existed until recently, now I guess I'll go on to forget about it..! – cjamesm Oct 26 '12 at 15:15

user207421 · Answer 4 · 2018-02-28T04:27:59.143

1

Put it inside a for(;;) loop and use continue instead of break. Put another break after the end of the switch statement to catch the cases that really do want to break:

for (;;)
{
    switch (x)
    {
    case case_that_wants_to_loop:
        // ...
        continue;
    case case_that_wants_to_break:
        // ...
        break;
    }
    break;
}

edited Feb 28 '18 at 04:27

answered Feb 28 '18 at 02:45

user207421

305,947
44
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@downvoter This technique is used in commercial interpreters. It is considerably more efficient than the alternatives, especially the ones that use a boolean variable. – user207421 Jun 17 '21 at 00:45

How to loop back to the beginning of a switch statement after a case

4 Answers4