C堆栈的链式存储

/*用单链表对堆栈操作*/
#include"stdio.h"
#define  maxsize  20

typedef struct node
{
    char data;
    struct node *next;
}lnode;

lnode *initializtion(lnode *top)
{
    top=NULL;
    return(top);

}

lnode *push(lnode *top,int x)
{
    lnode *p;
    p=(lnode*)malloc(sizeof(lnode));
    p->data=x;
    p->next=top;
    top=p;
    printf("[%p]",&top);
    return(top);

}

lnode *pop(lnode *top)
{

    lnode *tep;
    tep=top;
    top=top->next;
    free(tep);
    return(top);
}

void print(lnode *top)
{

    if(top==NULL)
    {
        printf("the stack is NULL");
        top->data=0;
     }
    else
    {
        while(top!=NULL)
        {
            printf("[%d]",top->data);
            top=top->next;
        }
    }
}

      
void main()
{
    int select;
    int x;
    int y;
    lnode *top;

    top=initializtion(top);

    do
    {
        printf("\n(1) Input a stack data");
        printf("\n(2) Output a stack data");
        printf("\n(3) Exit");
        printf("\nPlease select one:");
        scanf("%d",&select);

        switch(select)
        {
            case 1:printf("\nPlease input the data:");
                   scanf("%d",&x);
                   top=push(top,x);
                   printf("[%p]",&top);
                   printf("\nThis stack is: ");
                   print(top);
                   break;

            case 2:top=pop(top);
                   printf("\nThis stack is: ");
                   print(top);
                   printf("\nThe get data is: %d ",top->data);
                   break;

            case 3:break;
        }
    }
    while(select<3);
    getch();
}