Bad code or bad compiler?

musayume · 10-22-2001, 04:30 PM

Hello. I've just begun learning C and I've been practicing a few user input - calculation output programs. I got one program down that's doing fine... but I have one piece of code that's making me wonder if I'm missing something or if it's the compiler.

First, here's the code:

Code:

#include <stdio.h>

#define bleacher 5
#define	rsrvd 8
#define	box 12

FILE*fileout;

void main (void)
{
 int
	bleachnum,
	rsrvnum,
	boxnum,
	bleachrev,
	rsrvrev,
	boxrev,
	totalrev;

fileout = fopen ("A:RESULT.TXT","w");
printf ("\nPlease type in the number of bleacher seats sold:  ");
scanf ("%d",&bleachnum);
printf ("\nPlease type in the number of reserved seats sold:  ");
scanf ("%d",&rsrvnum);
printf ("\nPlease type in the number of box seats sold:  ");
scanf ("%d",&boxnum);

printf ("\nYou have entered %d bleacher seats, %d reserved seats and %d box seats.", bleachnum, rsrvnum, boxnum);
printf ("\n \n");
printf ("\nReport created at A:RESULT.TXT.");

bleachrev = bleacher * bleachnum;
rsrvrev = rsrvd * rsrvnum;
boxrev = box * boxnum;
totalrev = bleachrev + rsrvd + boxrev;

fprintf (fileout, "\nThe bleacher seats generated $%d.", bleachrev);
fprintf (fileout, "\nThe reserved seats generated $%d.", rsrvrev);
fprintf (fileout, "\nThe box seats generated $%d.", boxrev);
fprintf (fileout, "\nThe total revenue for the game is $%d.", totalrev);
fclose (fileout);
}

Well that's pretty much it. File generates fine, user input values come out fine. The only problem is that when I take a look at the RESULT.TXT file, the calculations become messed up.

BTW, I have inputed 5000, 7000, 8000, respectively, for all the values it asks.

For example, the line "box seats generated", it would say it generated $-1200. While the lines for bleacher and box seats would calculate fine. Also, the total revenue line would also have a negative result.

I tried this using Miracle C compiler for Windows.

I then tried compiling it under LCC-WIN32 compiler. This one compiled a little better. All the calculation result showed up correctly except the total revenue value was messed up. It gave some obscure number, 62098... which is questionable since theres no way the formula

totalrev = bleachrev + rsrvd + boxrev

would generate that number after inputting 5000, 7000, and 8000.

Anyways, is the code fine? Compiler gone mad?

Any recommendations on what Compiler I should use? I know alot of people recommend Linux compilers but I know just about nothing in operating Linux, atleast for now. Thanks.

10-22-2001, 04:42 PM

I think you may be running into overflow with your integers... depending on a few different factors (OS and compiler, probably), integers will only have a certain range of values (determined by the number of bytes attached to an int... I think you can find out for your system using the "sizeof()" function).

I compiled and ran your code using gcc compiler and a Windows 2000 machine, and got

The bleacher seats generated $25000.
The reserved seats generated $56000.
The box seats generated $96000.
The total revenue for the game is $121008.

As my output. So, check the size of an integer for your os/compiler... or just use a type of variable that has a larger range.

Hope that helps.

n9ski

QuestionC · 10-22-2001, 06:50 PM

Two things...
1. Your first problem, with the negative values, was probably some kind of overflow. ANSI C only requires that an int be able to hold values up to 32767, which is obviously not large enough for this application. longs must be able to reach 2147483647, which should be large enough for your purposes. Switch your code to use longs instead of ints. (This also means replacing all occourances of %d with %ld).

2. This is wrong...

Code:

totalrev = bleachrev + rsrvd + boxrev;

rsrvd? Are you sure you don't want to use rsrvrev instead of rsrvd?

musayume · 10-22-2001, 09:08 PM

Ah yes

That's one of the problem... I'm going to have to use understrikes from now on.

Thank you for all that replied

10-22-2001, 04:30 PM	#1
musayume Registered User Join Date: Oct 2001 Posts: 11	Bad code or bad compiler? Hello. I've just begun learning C and I've been practicing a few user input - calculation output programs. I got one program down that's doing fine... but I have one piece of code that's making me wonder if I'm missing something or if it's the compiler. First, here's the code: Code: #include <stdio.h> #define bleacher 5 #define rsrvd 8 #define box 12 FILEfileout; void main (void) { int bleachnum, rsrvnum, boxnum, bleachrev, rsrvrev, boxrev, totalrev; fileout = fopen ("A:RESULT.TXT","w"); printf ("\nPlease type in the number of bleacher seats sold: "); scanf ("%d",&bleachnum); printf ("\nPlease type in the number of reserved seats sold: "); scanf ("%d",&rsrvnum); printf ("\nPlease type in the number of box seats sold: "); scanf ("%d",&boxnum); printf ("\nYou have entered %d bleacher seats, %d reserved seats and %d box seats.", bleachnum, rsrvnum, boxnum); printf ("\n \n"); printf ("\nReport created at A:RESULT.TXT."); bleachrev = bleacher bleachnum; rsrvrev = rsrvd * rsrvnum; boxrev = box * boxnum; totalrev = bleachrev + rsrvd + boxrev; fprintf (fileout, "\nThe bleacher seats generated $%d.", bleachrev); fprintf (fileout, "\nThe reserved seats generated $%d.", rsrvrev); fprintf (fileout, "\nThe box seats generated $%d.", boxrev); fprintf (fileout, "\nThe total revenue for the game is $%d.", totalrev); fclose (fileout); } Well that's pretty much it. File generates fine, user input values come out fine. The only problem is that when I take a look at the RESULT.TXT file, the calculations become messed up. BTW, I have inputed 5000, 7000, 8000, respectively, for all the values it asks. For example, the line "box seats generated", it would say it generated $-1200. While the lines for bleacher and box seats would calculate fine. Also, the total revenue line would also have a negative result. I tried this using Miracle C compiler for Windows. I then tried compiling it under LCC-WIN32 compiler. This one compiled a little better. All the calculation result showed up correctly except the total revenue value was messed up. It gave some obscure number, 62098... which is questionable since theres no way the formula totalrev = bleachrev + rsrvd + boxrev would generate that number after inputting 5000, 7000, and 8000. Anyways, is the code fine? Compiler gone mad? Any recommendations on what Compiler I should use? I know alot of people recommend Linux compilers but I know just about nothing in operating Linux, atleast for now. Thanks.
musayume is offline

10-22-2001, 06:50 PM	#3
QuestionC Registered User Join Date: Sep 2001 Posts: 752	Two things... 1. Your first problem, with the negative values, was probably some kind of overflow. ANSI C only requires that an int be able to hold values up to 32767, which is obviously not large enough for this application. longs must be able to reach 2147483647, which should be large enough for your purposes. Switch your code to use longs instead of ints. (This also means replacing all occourances of %d with %ld). 2. This is wrong... Code: totalrev = bleachrev + rsrvd + boxrev; rsrvd? Are you sure you don't want to use rsrvrev instead of rsrvd?
QuestionC is offline

10-22-2001, 09:08 PM	#4
musayume Registered User Join Date: Oct 2001 Posts: 11	Ah yes That's one of the problem... I'm going to have to use understrikes from now on. Thank you for all that replied
musayume is offline

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10-22-2001, 04:42 PM	#2
Unregistered Guest Posts: n/a	I think you may be running into overflow with your integers... depending on a few different factors (OS and compiler, probably), integers will only have a certain range of values (determined by the number of bytes attached to an int... I think you can find out for your system using the "sizeof()" function). I compiled and ran your code using gcc compiler and a Windows 2000 machine, and got The bleacher seats generated $25000. The reserved seats generated $56000. The box seats generated $96000. The total revenue for the game is $121008. As my output. So, check the size of an integer for your os/compiler... or just use a type of variable that has a larger range. Hope that helps. n9ski