Seeking insight into a link Dave provided to someone

I need some kind of brilliant insight into the code at the following URL

http://www.daniweb.com/code/snippet266.html

The question stems from mygeti() in the following code.

Code:

#include <stdio.h>

int mygeti(int *result)
{
        char buff [ 13 ]; /* signed 32-bit value, extra room for '\n' and '\0' */
        return fgets(buff, sizeof buff, stdin) && sscanf(buff, "%d", result) == 1;
}

int main(void)
{
        int value;
        do {
                fputs("Enter an integer: ", stdout);
                fflush(stdout);
        } while ( !mygeti(&value) );
        printf("value = %d\n", value);
        return 0;
}

Isn't the line

Code:

char buff [ 13 ];

A bit non-portable? What happens if the code was compiled under a 16 bit machine? Or more to the point, any type of machine who's int type is not 32 bit. Wouldn't the code break?

No. sizeof(char) is always 1, and fgets's argument is sizeof buff, which is always 13. fgets() isn't like gets(), it takes a size parameter.

A bit non-portable? What happens if the code was compiled under a 16 bit machine? Or more to the point, any type of machine who's int type is not 32 bit. Wouldn't the code break?

Oh, I see. You mean, on some machines it might not be possible to enter every possible int value.

I've never seen a compiler with an int size of over 32 bits. But it's possible.

You're right, the array should probably be a little larger (perhaps BUFSIZ).

Originally Posted by cdalten

Isn't the line

Code:

        char buff [ 13 ]; /* signed 32-bit value, extra room for '\n' and '\0' */

A bit non-portable? What happens if the code was compiled under a 16 bit machine? Or more to the point, any type of machine who's int type is not 32 bit. Wouldn't the code break?

Yes, it's not portable -- that's part of the reason for the comment. I know a little compile-time thingy that can hard-code the correct size for an integer, but I didn't want to overcomplicate the snippet. And there is always the possibility of the user intering something like -1234567890abcdefghijkl. I chose not to get into that in the snippet.