Thread: A small question

You are looking for this i guess...

Code:

 
 
int main(void)
{
 
int count=10;
int i;
 
for(i=0;i<10;i++)
{
 
// do your stuff here .. will run for 10 times
 
}
 
 
return 0;
}

but if you want the user to decide when to exit you can have something like

Code:

int main(void)
{
int option=0;
 
while(option!=5)
{
 
// do your stuff
 
scanf("%d",option);
 
 
}
 
 
return 0;
}

so the code will run untill user enter 5 when asked for input..

or you could use an infinite for loop and break it in a specified condition :

Code:

#include<stdio.h>

int main(){
      for( ; ; ){
          ...
          if(<condition>)
                   break;         /* breaks the loop */
          ...
        }
return 0;
}

Originally Posted by Brain Cell

or you could use an infinite for loop and break it in a specified condition :

Code:

#include<stdio.h>

int main(){
      for( ; ; ){
          ...
          if(<condition>)
                   break;         /* breaks the loop */
          ...
        }
return 0;
}

Yuck!

Code:

#include<stdio.h>

int main()
{
    while(1)
    {
        ...
        if(<condition>)
            break;         /* breaks the loop */
        ...
    }
    return 0;
}

WaltP :
Will you explain why is it "yuck"?? if you don't know why then you shouldn't have commented on it in the first place

>WaltP:
>Will you explain why is it "yuck"??
I'm inclined to agree. An empty for loop is my preference for an infinite loop because I don't know of a compiler that gives me a warning when I try to use it. This is not so for your suggested while loop using a constant. And of course, since both are valid C, the only issue is one of style. Unless you know something that I don't of course.

>Unless you know something that I don't of course.
Like that's gonna happen. Prelude knows everything about C/C++.

Originally Posted by Brain Cell

WaltP :
Will you explain why is it "yuck"?? if you don't know why then you shouldn't have commented on it in the first place

Of course I know why. What makes you think I don't? I posted code that shows what I would use if I must, leaving you to compare and see if you can figure out why.

But my reasoning is a for loop is designed to start a loop indicator, process a comparison, and change the loop indicator. It's used to loop thru a number of specified iterations.

A while loop on the other hand is designed with a simple comparison in mind. And therefore less overhead (conceptually) than a for loop for an infinte loop.

If they were meant to be interchanagable, why have while loop at all? The designers of C would simply make you use

Code:

for ( ; i < 10; )

instead. It is functionally equivalent to

Code:

while (i < 10)

Therefore

Code:

while (1)  // instead of
for (;;)

To find the answer we have to see the assembly equalent for both....... any one interested in finding out(i dont knwo how assembly)..

I remember reading about while (1) having a redundant test for the true value, while for (;;) was automatically recognised as an intentional infinite loop, at least on some compilers.

Based on the publishing date of the book (early 1990s, I think), I thought it only applied to old compilers, and now both would be equivalent.
Funny that GCC didnt take that into account.

Anyway, partially because of what I read early on, I prefer using the for (;;) variant.