Thread: Arrays and sums of contents.

You've got a double array named payments[M], and a char array named l_plates[M][N], both of which have been sorted.

For the contents of l_plates that are THE SAME, you want the corresponding SUM of contents of payments stored on the first of equal slots, while turning the remaining equal slots into '-1' every time. How do you go about this?

Example: (why isn't this working?)

Code:

for (beg = 0, end = 0; beg < M-1; beg++) {
        for (end = beg + 1; (end < M) && (strcmp(l_plates[beg], l_plates[end]) == 0); end++) {}
        if (end > beg + 1) {
        payments[beg] = sum_pay(payments, beg, end);
        } 
    }


double sum_pay (double payments[M], int start, int finish) {
    int i, sum;
    
    for (i = start, sum = 0; (i < M) && (i < finish); i++) {
        sum = sum + payments[i];
    }
    for (i = start + 1; i < finish; i++) {
        payments[i] = -1;
    }
    return (sum);

What changes have to be made so that this code would work? I've been trying to figure this out for hours now...

Edit: this is just part of the code, of course. The whole thing does compile, and things seem to be working great until I get to this part (at least according to gdb).

Code:

int i, sum;

Is there a reason you declared sum as an int instead as a double?

Code:

for (end = beg + 1; (end < M) && (strcmp(l_plates[beg], l_plates[end]) == 0); end++) {}

Is there something the above loop is supposed to do? It does nothing right now.
Edit: Maybe, it is just setting end to a valid value; but, I think the value is 1 more than wanted.

Tim S.