breaking a loop

This is a discussion on breaking a loop within the C++ Programming forums, part of the General Programming Boards category; Sorry for the simple question - If i am in two loops and I put a break in the middle ...

  1. #1
    Frustrated Programmer :( phantom's Avatar
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    Question breaking a loop

    Sorry for the simple question -

    If i am in two loops and I put a break in the middle does it stop the loop it is in or does it stop all loops?

    Code:
    for(i=0; i<10; i++)
    {
           for(j=0; j<10; j++)
          {
              if(example[i][j]>100) {break;}
          }
    }
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  2. #2
    Programming Sex-God Polymorphic OOP's Avatar
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    Just the inner-most loop.

    If you want to exit BOTH loops, then put the double looping into it's own function and use return. Another alternative is to use goto BUT DONT DO THAT OR ELSE I WILL KILL YOU.

  3. #3
    It's full of stars adrianxw's Avatar
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    Better to design your loops with the exit routes already planned...

    Code:
    Continue = TRUE;
    i = -1;
    J = -1;
    
    while (Continue && (i < 10))
    {
        ++i;
        while (Continue && (j < 10))
        {
            ++j;
            if (example [i][j] > 100) Continue = FALSE;
        }
    }
    ... or similar.
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  4. #4
    Programming Sex-God Polymorphic OOP's Avatar
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    You generally don't want to do that because it forces an extra check every single time you go through your loops and adds another variable.

  5. #5
    Frustrated Programmer :( phantom's Avatar
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    thanks all for the help

    Another alternative is to use goto BUT DONT DO THAT OR ELSE I WILL KILL YOU.
    I remember programming in 'basic' and using GOTO, nowdays everyone threatens to kill you if you use it
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  6. #6
    It's full of stars adrianxw's Avatar
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    >>>
    You generally don't want to do that because it forces an extra check every single time you go through your loops and adds another variable.
    <<<

    The check on a simple boolean is very fast, and I like to have my escape routes planned at the design stage, easy to modify later. The variable would be a stack variable so I don't really care about that either.

    In any case, I expect the optimized code generated would be similar.
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  7. #7
    pronounced 'fib' FillYourBrain's Avatar
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    adrianxw is right. break, return (in the middle of a function), goto are similar in that they break out of a smooth flowing function. They "jump" in an assembly like way and not a high level language like way.
    "You are stupid! You are stupid! Oh, and don't forget, you are STUPID!" - Dexter

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