Thread: Access Violation

Aright, that cleared up a couple problems, but DevC++ still tells me that "emp[j++]->digits = numbr[i] - '0';" has an invalid type argument of '->'. What does that mean?

So at some point, you should probably think for two seconds. Do you want to write successive numbers in different emp structures? Do you even have an array of emp structures to start with? No? So emp[j++] is soooooo not going to work.

Edit: For that matter, you don't even have one emp structure. Why use malloc to create your structure? Just declare it and be done with it. But if you do have to use malloc, you do need to allocate enough space for that structure (sizeof(int) is NOT enough space).

Originally Posted by tabstop

So at some point, you should probably think for two seconds. Do you want to write successive numbers in different emp structures? Do you even have an array of emp structures to start with? No? So emp[j++] is soooooo not going to work.

Edit: For that matter, you don't even have one emp structure. Why use malloc to create your structure? Just declare it and be done with it. But if you do have to use malloc, you do need to allocate enough space for that structure (sizeof(int) is NOT enough space).

What I want to do is write successive numbers into the digits array, then use the different emp structures to later add, subtract, or compare the different strings with one another.

However, apparently I'm doing it wrong, since I keep crashingmy program before it can even get off the ground...

Originally Posted by Graham Aker

What I want to do is write successive numbers into the digits array

Exactly. The digits array in the same emp. So don't try to change emp with each digit! It can only lead to heartache.

Originally Posted by laserlight

So, at the moment you are dealing with one struct integer? You should know then that if emp->digit is a pointer to an int, *emp->digit is an int. Now, *(emp->digit + n) is equivalent to emp->digit[n]. Therefore, what you really wanted to write is emp->digit[j++].

That worked... Sorta. It's compiling now, and I've got one line on-screen, but it still is crashing somewhere...

Originally Posted by laserlight

tabstop referred to this line:

Code:

struct integer *num = (struct integer *)malloc(sizeof(int));

As I noted, one way to get the correct size is to use the expression being declared, i.e.,

Code:

struct integer *num = malloc(sizeof(*num));

But since at this point you just want to work with a struct integer to get the rest of the code right, you might as well create it on the stack:

Code:

struct integer num;

Consequently, you would not need to free the struct integer pointer (which you failed to do anyway). You would pass the address of num to readnum().

I probably implemented it wrong, but the third snippet broke the program- it wouldn't even compile.

The second, however, will still allow the program to compile.

Originally Posted by vart

I'm sure - he do not want this.
emp is pointer to one and only struct.

He has no array of struct pointers, no could you apply [] operator to strcut in C

what he probably want is closer to

Code:

emp->digits[j] = ...

Yeah, I've got that now already. A new problem popped up somewhere else...

You did read the part under it about passing &num to readnum instead of just num?

@Tabstop:...Whoops. I forgot that.

EDIT: Er, wait, now it's not even reading off the first line...

Okay, now it's telling me I have an Access Violation in the print function, which is right here:

Code:

      printf("\n The arrays are: ");
      for (k=0; k<stringnum; k++){
           for (i=0; i<j; i++)
               printf ("%d ", num[k].digits[i]);
      printf("\n");
      }

The problem line is "printf ("%d ", num[k].digits[i]);", and for some odd reason I think the problem involves that [k] bit there...