Remove trailing '+' sign in this output resulting from double for loops in C

Question

In the code attached, how do I modify it to remove Remove the trailing '+' signs.

int i,j,sum;
sum=1;

for(i=2; i<=10; i++) {
    for(j=1; j<(i+1); j++) {
        sum = sum + 1;
        printf("%d + ",j);
    }
    printf(" = %d", sum);
    printf("\n");
}

return EXIT_SUCCESS;

}

Here is the output:

1 + 2 +  = 3
1 + 2 + 3 +  = 6
1 + 2 + 3 + 4 +  = 10
1 + 2 + 3 + 4 + 5 +  = 15
1 + 2 + 3 + 4 + 5 + 6 +  = 21
1 + 2 + 3 + 4 + 5 + 6 + 7 +  = 28
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 +  = 36
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 +  = 45
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 +  = 55
  

Answer 1

You can't 'remove' output; you have to avoid generating it.

One way is to use:

for (int i = 2; i <= 10; i++)
{
    int sum = 0;
    const char *pad = "";
    for (int j = 1; j <= i; j++)
    {
        sum += j;
        printf("%s%d", pad, j);
        pad = " + ";
    }
    printf(" = %d\n", sum);
}

Note that this recalculates sum more directly, setting it to zero before the inner loop. It also minimizes the scope of the variables.

Answer 2

You can set and print the initial value in the outer loop. For my opinion also make it more readable. Furthermore you can use j instead of sum+1 for the addend

for (int i = 2; i <= 10; i++) {
    int sum = 1;
    printf("%d", sum);
    for (int j = 2; j<(i + 1); j++) {
        sum += j;
        printf(" + %d", j);
    }
    printf(" = %d", sum);
    printf("\n");
}