how to execute a statement every 3 iteration of loop?

Question

The language is C++ and I am trying to use system("cls") in a do{} while loop, but I don't want it to run this statement the first time or the second. I want this statement to run the 3rd time. is there any way to run this code inside a do-while loop after every 3 iteration of the loop? Thanks

Instead of `system("cls");`, I'd use something like [this](http://stackoverflow.com/a/7911218/179910). Much faster, and about the same degree of portability (i.e., none in either case). — Jerry Coffin, Dec 03 '14 at 18:31

score 2 · Accepted Answer · answered Dec 03 '14 at 18:33

Instead of i%3 as others have suggested, I'd avoid the (usually fairly slow) division operation and just reset the counter when it fires:

int i=0;
do { 
   if (++i == 3) {
       clear_screen();
       i = 0;
   }
} while (whatever());

Granted, when you're clearing the screen (especially via a system call) it's so slow the difference from avoiding division is a drop of water in the ocean, but cultivating good habits is a good thing, and in this case you gain speed with no loss of readability, so it's clearly a net gain.

score 1 · Answer 2 · answered Dec 03 '14 at 18:23

1

int i=0;
do
{
  i++;
  if(!(i % 3))
    system("cls");
}while(True)

answered Dec 03 '14 at 18:23

Ari0nhh

5,720
3
28
33

1

There is no reason to increase and check separately - `if( !( ++i % 3 ) )` IMHO more readable or even `if( ++i % 3 == 0 )` – Slava Dec 03 '14 at 18:52

score 1 · Answer 3 · answered Dec 03 '14 at 18:23

1

Yes, you can add a counter and provide an if conditon like as follows :-

int c=0;
do{
   c++
   ....
   ....
   if (c%3==0)
     system("cls");
   ...
   ...
  }while();

adjust this code as desired :-)

answered Dec 03 '14 at 18:23

3Demon

550
3
9

how to execute a statement every 3 iteration of loop?

3 Answers3