Exit two for loops if value is true

Question

How would I accomplish the following?

for (x=0;x<3;x++) {
    for (y=0;y<3;y++) {
        if (z == 1) {
            // jump out of the two for loops
        }
     }
}
// go on to do other things

If z=1, both for loops should stop and it should continue on with some other code. This obviously is an oversimplified example of what I'm trying to accomplish. (In other words, I know I need to initialize variables, etc...)

http://stackoverflow.com/questions/12612480/how-to-use-goto-to-break-a-nested-loop — beatgammit, Oct 26 '13 at 06:02
This is one situation when the use of `goto` might be appropriate. — , Oct 26 '13 at 06:05
I'm thinking goto at this point. The actual code is kinda messy for a break or any of the below solutiosn — codedude, Oct 26 '13 at 06:08
Definitely a duplicate of the above question. Didn't find that one somehow. Voted to close. — codedude, Oct 26 '13 at 06:09

score 5 · Answer 1 · answered Oct 26 '13 at 06:02

5

Assuming you don't need the values of y and x, just assign them the values that will case both loops to exit:

for (x=0;x<3;x++) 
{
    for (y=0;y<3;y++) 
    {
        if (z == 1) 
        {
           y = 3 ;
           x = 3 ;
        }
     }
}

answered Oct 26 '13 at 06:02

this

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3

Assuming the actual code doesn't do anything interesting after the internal loop – Leeor Oct 26 '13 at 06:06
@Leeor Yes, in that case more care should be taken. – this Oct 26 '13 at 06:08
I'm actually using the 2 for loops to go through a 2 dimensional matrix so this wouldn't really work. – codedude Oct 26 '13 at 06:18
@codedude how about this:http://stackoverflow.com/a/19603555/2327831 – this Oct 26 '13 at 06:19

score 2 · Answer 2 · answered Oct 26 '13 at 06:02

Add z to your outermost conditional expression, and break out of the innermost loop.

for(x = 0; x < 3 && z != 1; x++) {
    for(y = 0; y < 3; y++) {
        if(z == 1) {
            break;
        }
     }
 }

Of course, there's a fair bit of handwaving involved - in the code snippet you've provided, z isn't being updated. Of course, it'd have to be if this code was to work.

score 2 · Answer 3 · edited Oct 26 '13 at 06:33

2

for (x=0;x<3;x++) {
    for (y=0;y<3;y++) {
        if (z == 1) {
            // jump out of the two for loops
            x=y=3; //Set the x and y to last+1 iterating value 
            break; // needed to skip over anything outside the if-condition
        }
     }
}

edited Oct 26 '13 at 06:33

Zac Howland

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answered Oct 26 '13 at 06:02

P0W

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Added the needed break in the conditional block. It is needed in the case where there is something after the if-condition that does something (since he is wanting to break out of it at this point). – Zac Howland Oct 26 '13 at 06:34

score 1 · Answer 4 · answered Oct 26 '13 at 06:06

1

Have flag, and break it

int flag=0;

for(x = 0; x < 3; x++)  
{
   for(y = 0; y < 3; y++) 
   {
       if(z == 1)
       {
          flag=1;
          break;
       }
   }
   if(flag)
     break;
 }

answered Oct 26 '13 at 06:06

Kumareshan

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What's the point of putting `z` in the outermost conditional if you don't leverage it as part of the natural termination of the loop? – Makoto Oct 26 '13 at 06:07
I didn't see that Copy paste mistake – Kumareshan Oct 26 '13 at 06:10
If you flag the advantage is you break even if your logic is complex – Kumareshan Oct 26 '13 at 06:11

this · Accepted Answer · 2013-10-26T06:23:32.277

0

A good way to exit both loops and avoid any code that might follow the most inner loop is to put the loops in a function and return any value that you need.

for (x=0;x<3;x++) 
{
    for (y=0;y<3;y++) 
    {
        if (z == 1) 
        {
            return RETURN_VALUE
        }
        //avoids this code
    }
    //and this one too
}

edited Oct 26 '13 at 06:23

answered Oct 26 '13 at 06:13

this

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Say I had multiple if statements like the one above inside the for loops. If the first if statement was true and it returned some value would it then skip the next if statements? – codedude Oct 26 '13 at 18:14
1

When the function returns a value the function exits. – this Oct 27 '13 at 07:11

Exit two for loops if value is true

5 Answers5