链栈的实现

#include<bits/stdc++.h>
using namespace std;
struct stackk
{
   char value;
   stackk* nex;
};
void init(stackk *&s)
{
    s = (stackk*)malloc(sizeof(stackk));
    s->nex=NULL;
}
void push(int x,stackk *&s)
{
    stackk *tmp;
    tmp = (stackk*)malloc(sizeof(stackk));
    tmp->nex = s->nex;
    tmp->value=x;
    s->nex=tmp;
    return ;
}
void pop(stackk *s)
{
    s->nex=s->nex->nex;
    return ;
}
void destroy(stackk *&s)
{
    stackk *tmp;
    tmp=s->nex;

    while(tmp!=NULL)
    {
        free(s);
        s=tmp;
        tmp=s->nex;
    }
    free(s);
    return ;
}
void display(stackk *s)
{
    cout<<s->nex->value<<endl;
}
int main()
{
    int n;
    cin>>n;
    stackk *st;
    init(st);
    for(int i=1;i<=n;++i)
    {
        char b;
        char oper;
        cin>>oper;
        if(oper=='1')
            pop(st);
        else
        {
            cin>>b;
            push(b,st);
        }
        display(st);
    }
    destroy(st);
    return 0;
}