Breaking out of recursion and original function in C++

Question

So I am trying to figure out how to completely break out of a recursive function in C++.

In the example I have the two-dimensional array that holds the necessary information which is correct. In the event of no recursion everything works as expected - the part that returns time[start] breaks out of the function.

In the case of recursion, return breaks out of the current recursion, but the function itself continues to go on iterating every next i from the for loop. I would like the function to stop at this point.

Is there a way to break out of the function all together?

int findConn(int **computers, int *time, int *connections, int cnt, int k, int start){
    for (int i=0; i<cnt; i++){
        if ((computers[k][i]!=0)&&(i!=start)&&(i!=k)){
            if(computers[start][i]!=0){
                time[start]++;
                return time[start];
            } else {
                time[start]++;
                k=i;
                findConn(computers, time, connections, cnt, k, start);
            }
        }
    }
    return 0;
}

Possible duplicate of [Breaking out of a recursion in java](https://stackoverflow.com/questions/856124/breaking-out-of-a-recursion-in-java) — Saurav Sahu, May 24 '18 at 06:16
@SauravSahu - Throwing an exception as a flow of control mechanism is best avoided — StoryTeller - Unslander Monica, May 24 '18 at 06:23
@SauravSahu Java is designed to use exceptions as control flow, but C++ isn't. Doing so will degrade performance significantly — Passer By, May 24 '18 at 06:29
@StoryTeller if you're going to say that a correct and simple answer to a question should avoided, you should probably provide at least a little reasoning. — xaxxon, May 24 '18 at 06:38
@PasserBy I didn't say it was a an ideal solution, but it is a solution. — xaxxon, May 24 '18 at 06:40
@xaxxon - And yet you refrained from posting it as an answer where the community can properly review it. Wonder why. — StoryTeller - Unslander Monica, May 24 '18 at 06:41
@xaxxon `longjmp()` prevents proper destruction of local class instances. This may lead to memory leaks. So, the SauravSahu's hint with `throw`/`catch` might be performance critical (and ugly by design) but ensures proper stack unwinding. — Scheff's Cat, May 24 '18 at 06:50
@Scheff absolutely, but it looks like it would be ok in this particular example. — xaxxon, May 24 '18 at 07:20
@xaxxon :-) I saw this coming. Yepp - the presented sample code is rather C-like - nothing special from C++. So, in this case `longjmp()` would probably work. But even in this case, it's a bad general hint (without "but" and "be aware" - especially to somebody who's probably still learning the basics...) — Scheff's Cat, May 24 '18 at 07:24

jimmy · Answer 1 · 2018-05-24T06:36:52.343

-1

    const int nBreakAll = -1;
    int findConn(int **computers, int *time, int *connections, int cnt, int k, int start){
        for (int i=0; i<cnt; i++){
            ...
            if(break condition)
                 return nBreakAll;
            ....
            if ( nBreakAll  == findConn(...) )
            {
                 return nBreakAll; //this handles the break of recursive loop
            }
            //continues here
            ....

        }
        return 0;
    }

edited May 24 '18 at 06:36

answered May 24 '18 at 06:34

jimmy

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While this code may answer the question, providing additional context regarding why and/or how this code answers the question improves its long-term value. – Vishal Chhodwani May 24 '18 at 12:22

Breaking out of recursion and original function in C++

1 Answers1