Question

I am looking at the following piece of code:

void printd(int n)
{
     if (n < 0) {
         putchar('-');
         n = -n;
     }
     if (n / 10)
         printd(n / 10);
     putchar(n % 10 + '0');
}

I understand the first if statement fine, but the second one has me confused on a couple of points.

By itself, since “n” is an integer, I understand that n/10 will shift the decimal point to the left once – effectively removing the last digit of the number; however, I am having a little trouble understanding how this can be a condition by itself without the result being equal to something. Why isn’t the condition if ((n/10) >= 0) or something?

Also, why is the ‘0’ passed into the putchar() call?

Can someone tell me how it would read if you were to read it aloud in English?

Thanks!

Answer 1

The n / 10 will evaluate to false if the result is 0, true otherwise. Essentially it’s checking if n > 10 && n < -10 (the -10 doesn’t come into play here due to the n = -n code)

The + '0' is for character offset, as characters ‘0’-‘9’ are not represented by numbers 0-9, but rather at an offset (48-57 with ascii).

Can someone tell me how it would read if you were to read it aloud in English?

If you’re talking about the conditional, then I would say “if integer n divided by 10 is not zero”