Can I use break to exit multiple nested 'for' loops?

Is it possible to use the break function to exit several nested for loops?

If so, how would you go about doing this? Can you also control how many loops the break exits?

Solution 1:

No, don't spoil it with a break. This is the last remaining stronghold for the use of goto.

Solution 2:

AFAIK, C++ doesn't support naming loops, like Java and other languages do. You can use a goto, or create a flag value that you use. At the end of each loop check the flag value. If it is set to true, then you can break out of that iteration.

Solution 3:

Just to add an explicit answer using lambdas:

  for (int i = 0; i < n1; ++i) {
    [&] {
      for (int j = 0; j < n2; ++j) {
        for (int k = 0; k < n3; ++k) {
          return; // yay we're breaking out of 2 loops here
        }
      }
    }();
  }

Of course this pattern has a certain limitations and obviously C++11 only but I think it's quite useful.

Solution 4:

Another approach to breaking out of a nested loop is to factor out both loops into a separate function, and return from that function when you want to exit.

Of course, this brings up the other argument of whether you should ever explicitly return from a function anywhere other than at the end.