How to break out of nested loops?

Question

If I use a break statement, it will only break inner loop and I need to use some flag to break the outer loop. But if there are many nested loops, the code will

Answer 1

If you need the values of i and j, this should work but with less performance than others

for(i;i< 1000; i++){    
    for(j; j< 1000; j++){
        if(condition)
            break;
    }
    if(condition) //the same condition
        break;
}

Answer 2

Use this wise advice from LLVM team:

"Turn Predicate Loops into Predicate Functions"

See:

http://llvm.org/docs/CodingStandards.html#turn-predicate-loops-into-predicate-functions

Answer 3

A different approach is to refactor the code from two for loops into a for loop and one manual loop. That way the break in the manual loop applies to the outer loop. I used this once in a Gauss-Jordan Elimination which required three nested loops to process.

for (int i = 0; i < 1000; i++)
{
    int j = 0;

MANUAL_LOOP:;

    if (j < 1000)
    {
       if (condition)
       {
           break;
       }

       j++;
       goto MANUAL_LOOP;
    }
}