Question

I am preparing some code:

for(int a = 1; a <= 100; a++)    //loop a (main loop)
{
    for(int b = 1000; b <= 2000; b++)    //loop b
    {
       if(b == 1555)
          break;
    }

    for(int c = 2001; c <= 3000; c++)    //loop c
    {
       .
       .
       .
    }
}

I want to break the main loop (loop variable int a) by using a break; statement in the b loop (loop variable int b).

How can I do it?

Answer 1

I recommend refactoring your code into a function. Then you can just return from that function instead of using break:

void myFunc() 
{
    for(int a = 1; a <= 100; a++)    //loop a (main loop)
    {
        for(int b = 1000; b <= 2000; b++)    //loop b
        {
           if(b == 1555) // Logic is just an example,
              return;    // since it will always return
        }

        .
        .
        .
    }
}

This – or perhaps even a more involved refactoring of your code – should lend itself to a clean, elegant solution. Alternatively, if you just want a quick fix you could use a condition variable:

for(int a = 1; a <= 100; a++)    //loop a (main loop)
{
    bool cond = false;

    for(int b = 1000; b <= 2000; b++)    //loop b
    {
       if(b == 1555){
          cond = true;
          break;
       }
    }

    if (cond) break;

    .
    .
    .
}

---

Others have suggested using goto. While that is another quick fix, I strongly recommend against it, especially if you are working in a rigorous environment where the code will be peer reviewed and used for years down the road.

In my opinion the goto approach is a bit harder to maintain than a function/return refactoring, especially later on when someone else makes changes to the code. Plus you will have to justify the goto to anyone else on the team that happens to stumble onto the code.