Thread: Run-Time Check Failure #2

1. Where to you allocate num?
2. test[num] is outside the bounds of your array. C arrays start indexing at 0.
3. You declared your function as returning an int but failed to do so.
4. You never use your count variable, I am assuming you wanted to store the return value of fgets with it.

Originally Posted by mjskolly

Hi, I can't seem to figure this out. I ran this function and it worked the way I intended but although the output was correct I got this weird error.

Run-Time Check Failure #2 - Stack around the variable 'test' was corrupted.

Could someone point me in the direction about what I've done wrong?

thanks,
MIchelle

Code:

int correctionConversion(void)
{
	int count = 0;
	char test[num];
	printf("Please enter a string");
	fgets (test , num , stdin);
	test[num] = '\0';
	printf("%s", test);
	printf("if this program is working this should not be on a newline");

}

Ok... dig into your compiler settings and turn the warning levels all the way up... Then treat each warning as an issue to be dealt with... Your compiler should be screeching at you about an implicit declaration of num, num being used but never intialized to a value, missing return values, count being intialized but never used...

Considering that num would be implicitly created on the stack and it's initial contents would likely be an address-like value somewhere in range of your program's workspace (i.e. way the heck more than you intended), your test array could amount to several megabytes... created on a stack that is typically 1 megabyte....

All that because you left out the simple line ... int num = 100; and/or didn't declare your array specifically eg. char test[100]; or char test[MAXBUF];

This is C ... the devil is in the details.

HI, I declared num in the header.
Not where I would have intuitively put it but the teacher gave me ........ for not making all of my numbers into variables. When I declared it in the function the compiler said it needed to be a constant so i put it in the header with #defines num 12 .

For some reason the teacher seems to think we should define as much stuff as possible in the header, pretty much anything that is not going to change values.

I fixed it but now the program part doesnt work Now the newline is still there. At least that I can work with.
thanks

EDIT: I fixed the program but now I don't know why it worked in the first place earlier.
Learning is so much fun

Originally Posted by mjskolly

For some reason the teacher seems to think we should define as much stuff as possible in the header, pretty much anything that is not going to change values.

Your teacher is probably referring to constants defined with #define. Actually, it makes sense here, though you should rename num to something more descriptive and use the convention that macro names should be fully uppercase.

Originally Posted by mjskolly

EDIT: I fixed the program but now I don't know why it worked in the first place earlier.
Learning is so much fun

Pure dumb luck. You were writing out of bounds of your array which results in undefined behavior. You can read about what undefined behavior is. Read about how to get a line of text from the user.