栈结构

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <windows.h>
#define STACK_INIT_SIZE 20
#define STACKINCREMENT 10

typedef char ElemType;
typedef struct
{
   ElemType *top;
   ElemType *base;
   int stacksize;   
}sqStack;

//创建一个栈 
void InitStack(sqStack *s)
{
   s->base = (ElemType*)malloc(STACK_INIT_SIZE * sizeof(ElemType));  //内存中开辟一段连续空间作为栈空间 
   if(!s->base) printf("Init Error");    //失败检测 
   s->top = s->base;       //一开始栈顶就是栈底 
   s->stacksize = STACK_INIT_SIZE;  //设置最大容量 
}

//入栈操作 
void Push(sqStack *s,ElemType e)
{
   if(s->top - s->base >= s->stacksize)   //栈满追加空间 
      {
         //realloc函数改变指针指向的内存大小，而且原始内存中的数据保持不变,新的内存一定要大于以前的 
         s->base = (ElemType*)realloc(s->base,(s->stacksize + STACKINCREMENT)*sizeof(ElemType));
         if(!s->base)   printf("Push Error");    //分配内存失败 
         s->top = s->base + s->stacksize;                //重新定位栈顶指针 
         s->stacksize = s->stacksize + STACKINCREMENT;   //设置最大容量 
      }
   *(s->top) = e;    //放入数据 
   s->top++;         //栈顶指针上移 
}

//出栈操作 
void Pop(sqStack *s,ElemType *e)
{
   if(s->top == s->base)   return;  //栈空 
   *e = *--(s->top);   //下移栈顶指针取出数据 
}

//清空一个栈 
void ClearStack(sqStack *s)
{
   s->top = s->base;  //把栈顶指针指向栈底 
}

//销毁一个栈
void DestroyStack(sqStack *s)
{
   int i,len;
   len = s->stacksize;
   for(i=0;i<len;i++)
      {
         free(s->base);
         s->base++;   
      }
   s->base = s->top = NULL;
   s->stacksize = 0;   
}

//计算当前栈的容量
int StackLen(sqStack s)
{
   return (s.top - s.base);
}

int main()
{
   ElemType c;
   sqStack s;
   int len,i,sum=0;
   printf("Please input a Binary digit\n"); 
   InitStack(&s);    //创建一个栈，用来存放二进制字符串
   
   //输入二进制数
   scanf("%c",&c);
   while(c!='#')   //回车的键值 
      {
         Push(&s,c);
         scanf("%c",&c);
      }
   fflush(stdin);
   getchar();
   len = StackLen(s);   //得到栈中元素个数 
   for(i=0;i<len;i++)
      {
         Pop(&s,&c);
         sum = sum+(c-48)*pow(2,i);    //转换为十进制   
      }
   printf("Decimal is %d\n",sum);
   system("pause");
   return 0;   
}