[Spiffster]

I'm trying to learn C, and im having problems with a few loops. For example, I'll use my program that finds multiples of 6:

#include <stdio.h>

int main()
{
int i;
char ch;

/* display all multiples of 6 */
for(i=1; i<10000; i++){
if(!(i%6)){
printf("%d, more? y/n ", i);
ch= getchar();
if(ch=='n') break; /* stop the loop */
printf("\n");
}
}
}

Now it compiles cleanly, but something funny happens. The first time, the loop will function properly, now on the second time, (i think) it will skip the 'ch=getchar();' and then repeat again. The third time, it will function normally. And so on. The output looks like this.

6, more? y/n y

12, more? y/n
18, more? y/n y

24, more? y/n
30, more? y/n y

36, more? y/n
42, more? y/n n

Does anyone know why it doesn't ask for a character for the even loop iterations?

[int69h]

On 12, 24, and 36 it's getting the newline that's still in the input buffer.

Code:
ch=getchar();
getchar(); /* gobble up newline */

[Spiffster]

could you expand on that? please?

[parallax]

Originally posted by Spiffster:
could you expand on that? please?

When you input "y", what you're typing is {y} {return} which is "y\n".

You getchar the first time, which will retrieve the y, but the second time it retrieves the endline because that's still in stdin. You could getchar() again like the poster above mentioned or use fpurge(stdin) to clear the input buffer.

[snerdini]

Couldn't you also use scanf instead of getchar?