c语言进制转换 栈的操作

#include <stdio.h>  
#include <string.h>  
#include <stdlib.h> 
#include<math.h> 
#include <windows.h>
#define maxsize 20
#define Elemtype char  
typedef struct {
  Elemtype *top;
  Elemtype *bottom;
  int stack_size;
}stack;
void initial_stack(stack *s){
  s->bottom=(Elemtype*)malloc(maxsize*sizeof(Elemtype));
  if(!s->bottom){
    printf("error");
    exit(-1);
  }
  s->top=s->bottom;
  s->stack_size=maxsize;   
} 
void push(stack *s,Elemtype *e){
  if(s->top-s->bottom>=s->stack_size){
    s->stack_size+=maxsize;
    s->bottom=(Elemtype *)realloc(s->bottom,(s->stack_size+maxsize));
  }
  if(!s->bottom){
    exit(0);
  }
  *(s->top)=*e;
  s->top++;
}
void pop(stack *s,Elemtype *e){
  if(s->top==s->bottom){
    printf("栈空！\n");
  }
  else
  {
    *e=*--(s->top);
  }
}
int stack_len(stack s){
  return (s.top-s.bottom); 
}
int main(){
  stack s;
  Elemtype c;
  int len,i;
  int sum=0;
  printf("请输入二进制数\n");
  initial_stack(&s);
  scanf("%c",&c);
  while(c!='#'){
    push(&s,&c);
    scanf("%c",&c);
  }
  getchar();//去掉回车 
  len=stack_len(s);
  printf("\n栈的当前容量是%d\n",len);
  for(i=0;i<len;i++){
    pop(&s,&c);
    sum=sum+(c-48)*pow(2,i);
  }
  printf("\n二进制数转化为十进制:%d",sum);
  return 0;
}