Thread: Working with a number

I need to read in a 13 digit number which is barcode, and then I need to spit it out with hyphens added after the 3rd, 9th and 12th digit.

So if the user inputs barcode 1234567890123 then my program should output 123-456789-012-3

I'm learning how to code in a class and so we are restricted with what functions and whatnot we can use, so please bare with me.

What I have so far:

Code:

#include <stdio.h>
#include <assert.h>

#define UPPER_LIMIT 10000000000000LL
#define LOWER_LIMIT 1000000000000LL
#define FIRST_HYPHEN 10000000000LL
#define SECOND_HYPHEN 10000
#define THIRD_HYPHEN 10

int main(int argc, char *argv[]) {

    long long barcode = 0;
    int numScanned = -1;
    long long remainder = 0;

    printf("Enter your barcode: ");
    numScanned = scanf("%lld", &barcode);
    
    //Check that assumptions have been followed
    assert( (numScanned == 1) && ((barcode / LOWER_LIMIT) != 0) );
    
    remainder = barcode;
    
    long long i = LOWER_LIMIT;
    
    //Loop to get digits of barcode
    for (i = LOWER_LIMIT; i > 0; i = i / 10) {
        if ( (remainder / FIRST_HYPHEN == 0)
            || (remainder / SECOND_HYPHEN == 0)
            || (remainder / THIRD_HYPHEN == 0) ) {
            printf("-");
        } else {
            printf("%lld", remainder / i );
        }
        remainder = remainder % i;
    }
    
    printf("\n");
    
    return 0;
}

And it took me a while to figure out why with input 1234567890123 I'm receiving output 123-----------, but I realized it's because in my loop near the end,

Code:

 if ( (remainder / FIRST_HYPHEN == 0)
            || (remainder / SECOND_HYPHEN == 0)
            || (remainder / THIRD_HYPHEN == 0) ) {
            printf("-");
        } else {
            printf("%lld", remainder / i );
        }

This if statement means that it prints a hyphen after the 3rd digit as expected, but after that, the remainder is 1 digit less, but remainder / FIRST_HYPHEN == 0 is still true. What I intended for that if loop to do was to only be true if the remainder was 10 digits, 4 digits and 1 digit long. Any suggestions as to how I can work around this?

We haven't learnt how to use strings and whatnot in class yet, so we aren't allowed to use them. Also, another restriction added to us is that we have to read in the barcode as a single number of type long long, and not read each digit in.

I've tried that at first but a big problem I encountered was when 0's were present in the barcode at the start of nextsix or nextthree then it ignores them, so rather than an output of 123-456789-012-3 it gives 123-456789-12-3.

This is the main reason why I started using a loop.

Ok I answered the problem without looping, but I know this method will break down and become useless for the later stages of the assignment. Anyway, I'll cross that bridge when I get to it. Thanks quzah!

Oh I totally forgot about the extra 0's added by %03d, that's a great idea!