Best/common practice to delimit values in C when printing them.

Question

I tried the search function but only found questions regarding reading in comma/space delimited files.

My question is however, how do you usually approach this. Say I have a list/array/... of values, like {1, 2, 3, 4} and want to print them with a delimiter.

The simplest version would be something like:

#include <stdio.h>

int main(void)
{
     char list[] = {1, 2, 3, 4};
     unsigned int i;

     for (i = 0; i < 4; ++i)
     printf("%d, ", list[i]);

     return 0;
}

which will obviously print "1, 2, 3, 4, ". The problem I have with that is the comma and space character at the end.

Now I could do:

#include <stdio.h>

int main(void)
{
    char list[] = {1, 2, 3, 4};
    unsigned int i;

    for (i = 0; i < 4; ++i)
    {
        printf("%d", list[i]);
        if (i < 3)
            printf(", ");
    }

    return 0;
}

Bút that doesn't seem like the best way to do it. Can somebody point me into the right direction? Thanks

PS: No, I don't usually hardcode values
PPS: No, I am not trying to write .csv files ;)

Answer 1

I use this idiom:

assert(n > 0);
printf("%d", list[0]);
for (i = 1; i < n; ++i)
     printf(", %d", list[i]);

Its one disadvantage is that it doesn't scale nicely for n == 0, like a simple loop. Alternatively, you can add protection against n == 0:

if (n > 0)
    printf("%d", list[0]);
for (i = 1; i < n; ++i)
     printf(", %d", list[i]);

Answer 2

Use Michal Trybus's version or the reverse

for (i = 0; i < (n - 1); ++i) 
{
     printf("%d, ", list[i]);
}
printf("%d", list[n - 1]);

Answer 3

My standard technique for this is:

const char *pad = "";
for (int i = 0; i < n; i++)
{
    printf("%s%d", pad, list[i]);
    pad = ", ";
}

Sometimes, the initial value of pad is a blank, or a colon blank, or whatever else works in context.

Answer 4

for ( printf("%d",list[i=0]) ; i < n ; printf(", %d", list[++i]) ) ;

Answer 5

I picked up this format with the conditional operator from K&R2:

for (i = 0; i < n; i++)
    printf("%d%s", list[i], i+1 < n ? ", " : "\n");

Answer 6

Well even thought there is already an accepted answer, nobody has come with the obvious one to my taste:

#include <stdio.h>
int main(void) {
    unsigned list[] = {1, 2, 3, 4};
    unsigned const n = 4;
    if (n) for (unsigned i = 0; ; ++i) {
        printf("%d", list[i]);
        if (i >= n) break;
        printf(", ");
    }
    printf("\n");
    return 0;
}

Answer 7

Why not just another version while we're at it. Here's what I normally do

for (i=0;i<n;++i)
{
  if (i) printf(", ");
  printf("%d",list[i]);
}