Thread: Strange test results..

Hi, I'm writing a program that reads data out of a text file and into an array of "student" structures.

The array of structures is then sorted according to "grade". If two students have the same grade, they are sorted alphabetically.

The program works, but strangely, when I add another line of information to the text file, the program hangs at the end, as if it's waiting for more input. I don't understand why it would work for one text file, but not the other if they're both ended the same way.

If someone could take a look, it would really help me out. I guess I could pass this program in like this, but I'm just really curious as to why it wouldn't work for both of my text files.

This program is set up to be used in a Linux environment like so:

Code:

./ex11 < data

or, for the second data file (the one that causes an error in the program)

Code:

./ex11 < data2

Here's a url to download the application:
http://kouellette16.home.comcast.net/ex11.tar
This is my first time using the tar utility, lol. I hope I did it correctly.

Thanks again for any help.

In ex11.c

Code:

char c;

It should be int c since EOF is probably -1 and therefore outside the range of what char can hold.

Originally Posted by Aia

In ex11.c

Code:

char c;

It should be int c since EOF is probably -1 and therefore outside the range of what char can hold.

Really?

Code:

#include <stdio.h>
int main (void) {
	
	signed char a ; 
	a = -1 ; 
	printf("a is %i\n", a ) ; 
	return 0 ; 
}

Works for me. So, my point being, a char can represent a -1.

Todd (I didn't look at the OP's code - just replying to the comment)

> Works for me. So, my point being, a char can represent a -1.

_signed_ char is guaranteed to be able to hold any value from -127 to +127, but whether just plain char is signed or unsigned depends on the platform.

Solved

The problem was in my cmp function. Instead of returning the difference between the two values, i was just returning a -1, 0, or 1.