第一次写栈，撞墙啊！！求助

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define size 5

typedef struct
{
    int *base;
    int *top;
    int stack_size;
}zhan;


void setstack(zhan *s);//创栈
int isempty(zhan *s);//判空
int isfull(zhan *s);//判满
void enter(zhan *s,int a);//进栈
int gout(zhan *s);//出栈
void translate(int n,int b);//转换

int main()
{
    int n,b;
    printf("输入你要转换的整数");
    scanf("%d",&n);
    printf("输入要转换几进制");
    scanf("%d",&b);
    translate(n,b);
    getchar();
return 0;
}

void translate(int n,int b)//转换
{  
    int i;
    zhan *s;
    setstack(s);
    while(n)
    {
        enter(s,n%b);
        n=n/b;
    }
    while(!isempty(s))
    {
        i=gout(s);
        printf("%d",i);
    }
}

void setstack(zhan *s)//创栈
{
    s->base=(int*)malloc(size*sizeof(int));
    if(!s->base)exit(1);
    s->top=s->base;
    s->stack_size=size;
}

int isempty(zhan *s)//判空
{
    return s->top==s->base;
}

int isfull(zhan *s)//判满
{
    return s->top==(s->base+(size-1));
}

void enter(zhan *s,int a)//进栈
{
    if(isfull(s))
    {
        printf("栈满了");
        exit(1);
    }
    *s->top++=a;
}

int gout(zhan *s)//出栈
{
    if(isempty(s))
    {
        printf("栈空了");
        exit(1);        
    }
    return *--s->top;
}