在这个例子里，我们实现一个C语言版本的栈和C++语言的栈，通过比较两者的不同之处学习面向对象中数据的封装和抽象。
C语言版本：
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>struct Link
{int data;struct Link* next;
};struct Stack
{struct Link* head;int size;
};void StackInit(struct Stack* stack)
{stack->head = NULL;stack->size = 0;
}void StackPush(struct Stack* stack, const int data)
{struct Link* node;node = (struct Link*)malloc(sizeof(struct Link));assert(node != NULL);node->data = data;node->next = stack->head;stack->head = node;++stack->size;
}int StackEmpty(struct Stack* stack)
{return (stack->size == 0);
}int StackPop(struct Stack* stack, int* data)
{if (StackEmpty(stack)){return 0;}struct Link* tmp = stack->head;*data = stack->head->data;stack->head = stack->head->next;free(tmp);--stack->size;return 1;
}void StackCleanup(struct Stack* stack)
{struct Link* tmp;while (stack->head){tmp = stack->head;stack->head = stack->head->next;free(tmp);}stack->size = 0;
}int main(void)
{struct Stack stack;StackInit(&stack);int i;for (i=0; i<5; i++){StackPush(&stack, i);}while (!StackEmpty(&stack)){StackPop(&stack, &i);printf("%d ", i);}printf("\n");return 0;
}C++语言版本：
#include <iostream>
using namespace std;
class Stack
{struct Link{int data_;Link* next_;Link(int data, Link* next) : data_(data), next_(next){}};
public:Stack() : head_(0), size_(0){}~Stack(){Link* tmp;while (head_){tmp = head_;head_ = head_->next_;delete tmp;}}void Push(const int data){Link* node = new Link(data, head_);head_ = node;++size_;}bool Empty(){return (size_ == 0);}bool Pop(int& data){if (Empty()){return false;}Link* tmp = head_;data = head_->data_;head_ = head_->next_;delete tmp;--size_;return true;}private:Link* head_;int size_;
};// 避免名称冲突
// 类型的扩充
// 数据封装、能够保护内部的数据结构不遭受外界破坏
int main(void)
{Stack stack; // 抽象数据类型 类类型int i;for (i=0; i<5; i++){//StackPush(&stack, i);stack.Push(i); // this = &stack}//while (!StackEmpty(&stack))while (!stack.Empty()){//StackPop(&stack, &i);//printf("%d ", i);stack.Pop(i);cout<<i<<" ";}//printf("\n");cout<<endl;return 0;
}