Ok, I'm working with using member functions in structures in C, which I've never done before, and I'm stuck. Here's the code:

typedef struct Node
{
 char data;
 struct Node* next;
}node,*node_ptr;
typedef struct stack
{
 node* head;
 int length;
 void (*push)(char,node_ptr);
 char (*pop)(node_ptr);
}stack,*stack_ptr;
void push(char info,node_ptr head)
{
 node_ptr current;
 current=(node *)malloc(1);
 current->data=info;
 current->next=head;
 head=current;
}
char pop(node_ptr head)
{
 node_ptr current;
 char input;
 input=head->data;
 head=head->next;
 free(current);
 return(input);
}

Now my problem is that I don't want to have to reference a node as a variable to push and pop, I want to use the head of the stack as the only node they will modify. How would I go about doing this?

This message was edited by stober at 2005-8-8 8:13:52

---

C does not really have c++ style member functions -- they are just global functions that can be called at any time anywhere in the program.

Here is one way to solve your proglem, which uses pointer-to-pointer. Also note the change to malloc() in push(), your program was not allocating enough memory for the node structure.

typedef struct Node
{
 char data;
 struct Node* next;
}node,*node_ptr;

typedef struct stack
{
 node* head;
 int length;
 void (*push)(char,node_ptr);
 char (*pop)(node_ptr);
}stack,*stack_ptr;

void push(char info,node_ptr* head)
{
	node_ptr current;
	current=(node *)malloc(sizeof(struct Node));
	current->data=info;
	current->next = 0;
	if(*head == 0)
	{
		*head = current;
	}
	else
	{
		// find the tail
		node_ptr n = *head;
		while(n->next != 0)
			n = n->next;
		// add node to the end of the list
		n->next = current;
	}
}

char pop(node_ptr* head)
// removes the head node of the linked list
// in FIFO (first in, first out)
{
 node_ptr current;
 char input;
 if(*head == 0) return 0;
 current = *head;
 *head = current->next;
 input = current->data;
 free(current);
 return(input);
}

int foo()
{
	struct stack stk;
	stk.head = 0;
	stk.length = 0;

	push('A',&stk.head);
	pop(&stk.head);
	return 0;
}

Thanks for the help, you killed two birds with one stone.