栈的应用 后缀表达式求值

#include
#include
#include

//栈的数据类型
typedef int SElemType ;

//链栈的数据类型C语言描述

typedef struct stack
{

	SElemType data;
	struct snode *next;
}Snode,*LinkStack;

//1.初始化操作
void initLinkStak(LinkStack *LS)
{
	*LS=NULL; 
}

//2.判断栈是否空
int LinkStackEmpty(LinkStack LS)
{
	if(LS==NULL) return 1;
	else return 0;
}

//3.得到栈顶
int LinkStackGetTop(LinkStack LS,SElemType *e)
{
	if(LS==NULL) return 0;
	*e=LS->data;return 1;
}

//4.求栈的长度
int LinkListLength(LinkStack LS)
{
	LinkStack p=LS;
	int n=0;
	while(p){n++;p=p->next;}
	return n;
}

//5.进栈
void Push(LinkStack *LS,SElemType e)
{
	//生成新的结点插入到原来的第一个节点之前，头插法
	LinkStack p=(LinkStack)malloc(sizeof(Snode));
	p->data=e;
	p->next=*LS;*LS=p;
}

//6.出栈
void Pop(LinkStack *LS,SElemType *e)
{
	LinkStack p=*LS;
	if(*LS==NULL)return 0;
	*e=p->data;
	*LS=(*LS)->next;
	free(p);
	return 1;
}

//后缀表达式求值
void suffix_value(char data[]);  

void main()
{
	char data[80];
	printf("请输入表达式:\n"); //输入表达式，允许出现() [] {}
	gets(data);
	suffix_value(data);
}

//后缀表达式求值
void suffix_value(char data[])
{

	LinkStack S;
	int i=0,x1,x2,result;
	initLinkStak(&S);
	while(data[i]!='#')
	{
		switch(data[i])
		{
		case '+':Pop(&S,&x2);Pop(&S,&x1);Push(&S,x1+x2);break;
		case '-':Pop(&S,&x2);Pop(&S,&x1);Push(&S,x1-x2);break;
		case '*':Pop(&S,&x2);Pop(&S,&x1);Push(&S,x1*x2);break;
		case '/':Pop(&S,&x2);Pop(&S,&x1);if(x2!=0)Push(&S,x1/x2);else{printf("分母为0!\n");return 0;}
		case 32:break;
		default:Push(&S,data[i]-48);   //将字符转换为整数送栈
		}
		i++;
	}
	Pop(&S,&result);
	printf("结果=%d\n",result);
}