CODEWITHSUNDEEP
loopsc++11goto
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GuessMe

Reputation: 13

Issue using for loop and goto statement

I am using C++11 std::list and list iterators. I use nested loops and test a condition and if it succeeds, I use goto statement to get out. A pseudo code is shown below:

std::list<myclass>::iterator tmpItr;
std::list<myclass>::iterator tmpItr2;
std::list<std::list<myclass>::iterator>::iterator radItr;
double cutoffVal = someVal;
double currVal = 0.0;

for (radItr=radList.begin();radItr!=radList.end();radItr++) {
    tmpItr2 = *radItr;
    for (tmpItr=pList.begin();tmpItr!=pList.end();tmpItr++) {
         if (tmpItr == tmpItr2)
             continue;

         /* Some Operation Here */
         currVal += NewVal;
         if (currVal >= cutoffVal)
             goto BREAKLOOP;
    }
}

BREAKLOOP:
// Use tmpItr and tmpItr2

My problem is that sometime the value of tmpItr goes to list.end() and I get a segmentation fault. Does the goto statement somehow does post increment as well here?

Upvotes: 1

Views: 104

Answers (2)

Toby Speight
Toby Speight

Reputation: 30827

I think your problem occurs when the goto is not reached:

for (...;  radItr != radList.end();  ...) {
    for (...;  tmpItr != pList.end();  ...) {
         if (...)
             goto BREAKLOOP;
    }
}

// At this point, radItr==radList.end() && tmpItr==pList.end()

BREAKLOOP:

Upvotes: 0

dufresnb
dufresnb

Reputation: 135

I'm not positive it will fix the problem with your iterators, but most people I talk to consider goto's in c++ to be bad code. Why not replace goto with:

  (bool)breakout=true;
  break;
  }
if(breakout)break;

Upvotes: 1

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