（1）stack.h
/*****************************************************************************
* *
* ------------------------------- stack.h -------------------------------- *
* *
*****************************************************************************/
#ifndef STACK_H
#define STACK_H
#include <stdlib.h>
#include "list.h"
#include "stack.h"
/*****************************************************************************
* *
* Implement stacks as linked lists. *
* *
*****************************************************************************/
typedef List Stack;
/*****************************************************************************
* *
* --------------------------- Public Interface --------------------------- *
* *
*****************************************************************************/
#define stack_init list_init
#define stack_destroy list_destroy
int stack_push(Stack *stack, const void *data);
int stack_pop(Stack *stack, void **data);
#define stack_peek(stack) ((stack)->head == NULL ? NULL : (stack)->head->data)
#define stack_size list_size
/*****************************************************************************
* *
* ------------------------------- stack.c -------------------------------- *
* *
*****************************************************************************/
/*****************************************************************************
* *
* ------------------------------ stack_push ------------------------------ *
* *
*****************************************************************************/
int stack_push(Stack *stack, const void *data) {
/*****************************************************************************
* *
* Push the data onto the stack. *
* *
*****************************************************************************/
return list_ins_next(stack, NULL, data);
}
/*****************************************************************************
* *
* ------------------------------ stack_pop ------------------------------- *
* *
*****************************************************************************/
int stack_pop(Stack *stack, void **data) {
/*****************************************************************************
* *
* Pop the data off the stack. *
* *
*****************************************************************************/
return list_rem_next(stack, NULL, data);
}
#endif
（2）ex-1.c
/*****************************************************************************
* *
* ex-1.c *
* ====== *
* *
* Description: Illustrates using a stack (see Chapter 6). *
* *
*****************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include "list.h"
#include "stack.h"
/*****************************************************************************
* *
* ------------------------------ print_stack ----------------------------- *
* *
*****************************************************************************/
static void print_stack(const Stack *stack) {
ListElmt *element;
int *data,
size,
i;
/*****************************************************************************
* *
* Display the stack. *
* *
*****************************************************************************/
fprintf(stdout, "Stack size is %d\n", size = stack_size(stack));
i = 0;
element = list_head(stack);
while (i < size) {
data = list_data(element);
fprintf(stdout, "stack[%03d]=%03d\n", i, *data);
element = list_next(element);
i++;
}
return;
}
/*****************************************************************************
* *
* --------------------------------- main --------------------------------- *
* *
*****************************************************************************/
int main(int argc, char **argv) {
Stack stack;
int *data,
i;
/*****************************************************************************
* *
* Initialize the stack. *
* *
*****************************************************************************/
stack_init(&stack, free);
/*****************************************************************************
* *
* Perform some stack operations. *
* *
*****************************************************************************/
fprintf(stdout, "Pushing 10 elements\n");
for (i = 0; i < 10; i++) {
if ((data = (int *)malloc(sizeof(int))) == NULL)
return 1;
*data = i + 1;
if (stack_push(&stack, data) != 0)
return 1;
}
print_stack(&stack);
fprintf(stdout, "Popping 5 elements\n");
for (i = 0; i < 5; i++) {
if (stack_pop(&stack, (void **)&data) == 0)
free(data);
else
return 1;
}
print_stack(&stack);
fprintf(stdout, "Pushing 100 and 200\n");
if ((data = (int *)malloc(sizeof(int))) == NULL)
return 1;
*data = 100;
if (stack_push(&stack, data) != 0)
return 1;
if ((data = (int *)malloc(sizeof(int))) == NULL)
return 1;
*data = 200;
if (stack_push(&stack, data) != 0)
return 1;
print_stack(&stack);
if ((data = stack_peek(&stack)) != NULL)
fprintf(stdout, "Peeking at the top element...Value=%03d\n", *data);
else
fprintf(stdout, "Peeking at the top element...Value=NULL\n");
print_stack(&stack);
fprintf(stdout, "Popping all elements\n");
while (stack_size(&stack) > 0) {
if (stack_pop(&stack, (void **)&data) == 0)
free(data);
}
if ((data = stack_peek(&stack)) != NULL)
fprintf(stdout, "Peeking at an empty stack...Value=%03d\n", *data);
else
fprintf(stdout, "Peeking at an empty stack...Value=NULL\n");
print_stack(&stack);
/*****************************************************************************
* *
* Destroy the stack. *
* *
*****************************************************************************/
fprintf(stdout, "Destroying the stack\n");
stack_destroy(&stack);
return 0;
}