Thread: A Quick Question about Stacks

Hi all. I'm new to this place, but I am really stuck and I figure maybe this is the place to go. The following peice of code is EXACTLY what my professor gave the class, and is the only demonstration of stacks he gave us. But, when you try to push items onto the stack, I get an error message! I don't even think the single bit of code he gave us is correct! when i compile (we have to compile under gcc) i get the following error message:

incompatible type for argument 1 of `push'

This is my code:

Code:

#include <stdio.h>

#define MAXSTACK 20

     struct arraystack {
	int items[MAXSTACK];
	char quality[MAXSTACK];
	int top;
};
void push( struct arraystack *produce, int x, char q );
void  pop( struct arraystack *produce ,int *xx, char *qq);

int main( )
{

struct arraystack factory ;	

factory.top = -1;

push( factory, 4, 'd');  //This is where the error comes in
return 0;
}

void push( struct arraystack *produce, int x, char q )
{
	if ( produce->top >= MAXSTACK - 1 )
	  {
	     printf( "\n% Stack is full.\n");
	  } 
        else {
		produce -> top = produce -> top + 1;
		produce -> items[ produce -> top ] = x;
		produce -> quality[ produce -> top ] = q;
	     }
}

void  pop( struct arraystack *produce ,int *xx, char *qq)
{
	int x = 0;
	if ( produce->top < 0 )
	{
	printf("\nStack is empty");
	}
	 else {
		*xx = produce -> items[ produce ->top ];
		*qq = produce -> quality[ produce ->top ];
		produce -> top = produce -> top - 1;
	      }
}

what gives????

looks like you need to pass the address of your factory variable, it wants a pointer.

what's "factory" ? Try using arraystack.top instead of factory.top..

Originally Posted by durban

you aren't initializing factory correctly. Try,

arraystack factory = new arraystack;

The first rule of C programming is, there is no 'new' in C programming.

Originally Posted by durban

you aren't initializing factory correctly. Try,

arraystack factory = new arraystack;

lool Dude, you are on hardcore programming grounds. There are no objects like in higher languages here

Originally Posted by rockytriton

looks like you need to pass the address of your factory variable, it wants a pointer.

Indeed. And you need & to pass the address.

Code:

push( &factory, 4, 'd');

ouch..havent seen the code properly before. I didn't see that factory is a pointer to your struct. Yes. Like the man before me said, pass the address of the variable. See how push and pop are defined. THey both expect a pointer as the first argument.