C语言对栈的实现基本操作

#include <stdio.h>#include <malloc.h>#include <stdlib.h>#include <stdbool.h> typedef struct Node{ int data; struct Node * pNext;}NODE, * PNODE; typedef struct Stack{ PNODE pTop; PNODE pBottom;}STACK, * PSTACK; //PSTACK等价于struct STACK * void init(PSTACK); //初始化栈void push(PSTACK, int ); //压栈void traverse(PSTACK); //遍历bool pop(PSTACK pS,int * pVal); //出栈void clear(PSTACK pS); //清空栈 int main(void){ STACK S; //STACK等价于struct Stack int val; init(&S); //造出空栈  push(&S, 1); //压栈 push(&S, 2); push(&S, 3); push(&S, 4); push(&S, 5); push(&S, 6);  traverse(&S); //遍历输出/* if(pop(&S,&val)) { printf("出栈成功，出栈的元素是%d/n", val); } else { printf("出栈失败！/n"); }*/  clear(&S); traverse(&S);  return 0;} void init(PSTACK pS){ pS->pTop = (PNODE)malloc(sizeof(NODE)); if(NULL == pS->pTop) { printf("动态内存分配失败/n"); exit(-1); } else { pS->pBottom = pS->pTop; pS->pTop->pNext = NULL; }} void push(PSTACK pS, int val){ PNODE pNew = (PNODE)malloc(sizeof(NODE)); //创建新的节点 pNew->data = val; //将val的值赋给新节点的数据域 pNew->pNext = pS->pTop; //将新节点的指针域指向下一个节点.pS->Top不能改写成pS->Bottom pS->pTop = pNew; //pTop指向新节点 return;} void traverse(PSTACK pS){ PNODE p = pS->pTop; while(p != pS->pBottom) { printf("%d ", p->data); p = p->pNext; } printf("/n"); return;} bool empty(PSTACK pS){ if(pS->pTop == pS->pBottom) { return true; } else { return false; }} bool pop(PSTACK pS,int * pVal){ if(empty(pS)) { return false; } else { PNODE r = pS->pTop; *pVal = r->data; pS->pTop = r->pNext; free(r); r = NULL; return true; }} //清空栈void clear(PSTACK pS){ if(empty(pS)) //如果 { return; } else { PNODE p = pS->pTop; //定义元素p指向栈顶元素 PNODE q = NULL； //定义元素q，初始值为空   while(p !=pS->pBottom) //如果栈不为空 {  q = p->pNext; //q指向p的下一个元素  free(p);  //释放p所指向的栈顶元素  p = q;  //将q所指向的元素赋给p } pS->pTop = pS->pBottom;  }}