栈的基本构造

#include<stdio.h>

#include<stdlib.h>

 

typedef struct Node

{

    int data;

    struct Node * pNext;

}NODE, *PNODE;

 

typedef struct Stack

{

    PNODE pTop;//指向栈顶

    PNODE pBottom;//指向栈底下一个无实际意义结点

}STACK, *PSTACK;

 

void init(PSTACK);   //初始化，建造空栈

void push(PSTACK, int);  //压栈

void traverse(PSTACK);   //遍历

int pop(PSTACK, int *); //出栈

void clear(PSTACK);  //清空

 

int main()

{

    STACK S;

    int val;

 

    init(&S);

    push(&s, 1);
    push(&s, 2);
    push(&s, 3);
    push(&s, 4);
    push(&s, 5);

     //push(&S, val);

    }

 

    traverse(&S);

 

    if(pop(&S, &val))

        printf("\npop succeded! The element you have delivered from godown is %d!\n",val);

    else

        printf("\npop failed!\n");

    traverse(&S);

    return 0;

}

void init(PSTACK pS)

{

    pS->pTop = (PNODE)malloc(sizeof(NODE));

    if(NULL == pS->pTop)

    {

        printf("out of memory!\n");

        exit(-1);

    }

    else

    {

        pS->pBottom = pS->pTop;

        pS->pBottom->pNext = NULL;

    }

}

 

void push(PSTACK pS, int val)

{

    PNODE pNew = (PNODE)malloc(sizeof(NODE));

    pNew->data = val;

    pNew->pNext = pS->pTop;

    pS->pTop = pNew;

}

 

void traverse(PSTACK pS)

{

    PNODE p = pS->pTop;

    while(p != pS->pBottom)

    {

        printf("%d ", p->data);

        p = p->pNext;

 

    }

    printf("\n");

}

 

int empty(PSTACK pS)

{

    if(pS->pTop == pS->pBottom)

        return 1;

    else

        return 0;

}

int pop(PSTACK pS, int *pval)

{

    if(empty(pS))

    {

        return 0;

    }

    else

    {

        PNODE p = pS->pTop;

        pS->pTop = p->pNext;

        *pval = p->data;

        free(p);

        p = NULL;

 

        return 1;

    }

}

 

void clear(PSTACK pS)

{

    if(empty(pS))

        return;

    else

    {

        PNODE p = pS->pTop;

        PNODE q = NULL;

 

        while(p != pS->pBottom)

        {

            q = p->pNext;

            free(p);

            p = NULL;

            p = q;

        }

        pS->pTop = pS->pBottom;

    }

}