Thread: Function help

Allight here is my function i am getting a negative output for Track revenue . the number is right but it negative. How do i fix it and also who do i shorten/ make my code more efficient. Thanks

Code:

void writers (int cid [ ], double cidvalue [ ], int count)
{
	FILE* dancef = fopen ("tracks.dat", "rt");
	FILE* annf = fopen ("recp.rpt", "wt");
	int numvtracks = 0;
	int numitracks = 0;
	int numl, cidnum1, cidnum2;
	double track1, track2, tprice;
	double total = 0.0;
	int ftrack1, ftrack2;
	char sPin [16];
	while (count > 0)
	{
		numl = fscanf (dancef, "%d %d %12s\n", &cidnum1, &cidnum2, &sPin);
		if (numl != 3) break;
                fprice1 = search (cid, cidvalue, count, cidnum1, &track1);
		fprice2 = search (cid, cidvalue, count, cidnum2, &track2);
		if (ftrack1 && ftrack2 && (cidnum1 != cidnum2))
		{
			tprice =  (track2 - track1);
			total += tprice;
			numvtracks++;
			fprintf (annf, "%s   %2d   %2d   $%5.2lf\n", sPin, cidnum1, cidnum2, tprice);
		}
		else
		{
			fprintf (annf, "INVALID DATA: %2d  %2d *\n", cidnum1, cidnum2);
			numitracks++;
		}
	}
	fclose (annf);
	fclose (dancef);
	printf ("\ntracks processed: %d\n", numvtracks);
	printf ("invalid tracks processed: %d\n", numitracks);
	printf ("Track revenue: $%.2lf\n", total);

I'm going to take a shot at this despite very weak knowledge of C and programming in general.

It seems that track revenue is stored in the variable 'total' which is calculated from substracting 'track2' from 'track1'.

However, as I see from your code you have not stored anything in those two variables, nor have you even initialized them. If you don't initialize a variable, the existing data in the peice of memory that has been allocated will still be there. Therefore yielding undefined results when any sort of computation is performed upon them or with them.

I have absolutely no idea what your goal is because your code is so obscure to me, but I'm pretty certain that what I've stated is why your getting negative results.

> while (count > 0)
Use a debugger, put a breakpoint on this line.

When you hit the breakpoint, add say 'total' to a watch window, then single step the code and observe.

When expectation != reality, you've found a bug.

And we don't have all your code, so I guess we're all out of luck.

Which compiler are you using?
Most compilers of any usefulness come with a debugger.

Originally Posted by jafa401

ok I want to make my code more efficient and tight
i feel like i could do this code in less number of lines
i just can't figure out how

IMO the code is fine already. The flow of execution makes sense, it's readable, there are no obvious inefficiencies or pointless quirks.