栈应用之使用逆波兰输入求表达式的值

#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>

#define OK 		1
#define ERROR 		0
#define STACK_INIT_SIZE 20
#define STACK_INCREMENT 10
#define DIGITBUFFER 	10

typedef int    Status;
typedef double Elemtype;
typedef struct StackNode{
	Elemtype* base;
	Elemtype* top;
	int stackSize;
}StackNode;
typedef struct StackNode* Stack;

Status InitStack(Stack s){
	s->base = (Elemtype*)malloc(sizeof(Elemtype) * STACK_INIT_SIZE);
	if(!s->base)
		return ERROR;
	s->top = s->base;
	s->stackSize = STACK_INIT_SIZE;
	return OK;
}
Status Pop(Stack s,Elemtype* result){
	if(s->base == s->top)
		return ERROR;
	*result = *(--s->top);
	return ERROR;
}
Status Push(Stack s,Elemtype value){
	if(s->top - s->base == s->stackSize){
		s->base = (Elemtype*)realloc(s->base,sizeof(Elemtype) * (STACK_INIT_SIZE + STACK_INCREMENT));
		if(!s->base)
			return ERROR;
		s->top = s->base + STACK_INIT_SIZE;
		s->stackSize = STACK_INIT_SIZE + STACK_INCREMENT;
	}
	*(s->top) = value;
	s->top++;
	return OK;
}
int StackLenth(Stack s){
	return s->top - s->base;
}
Status RPT(){			//reverse polish notation
	char c;
	double operater1,operater2;
	double result;
	int i = 0;
	char bufferDigit[DIGITBUFFER];

	Stack s;
	InitStack(s);

	printf("  Please Enter Reverse Polish Notation!(RPN)\n");
	printf("------note:  separated by space between -------\n");
	printf("------     number or operator.end of '#'-------\n");

	scanf("%c", &c);
	while(c != '#'){
		/* 处理输入的数字：由于使用%c接受输入，所以对于123这样的多位数的
		 * 输入%c是不能处理的。所以设置了char型的数组bufferDigit来缓存输
		 * 入的多位数。在开始了多位数的输入之后，必将以空格来结束该多位数
		 * 输入，所以if(c == ' ')用来判断多位数的结束。以便将缓存在char
		 * 型数组中的多位数转化为double并且Push。
		 */
		while( isdigit(c) || c == '.'){
			if(i == 10){
				printf("number is too lager\n");
				return ERROR;
			}
			bufferDigit[i++] = c;
			bufferDigit[i] = '\0';
			scanf("%c", &c);
			if(c == ' '){	//不是空格就一定还是数字
				result = atof(bufferDigit);
				Push(s,result);
				i = 0;
			}
		}
		/* 处理输入的运算符
		 */
		switch(c){
			case '+':
				Pop(s,&operater1);
				Pop(s,&operater2);
				Push(s,operater1 + operater2);
				break;
			case '-':
				Pop(s,&operater1);
				Pop(s,&operater2);
				Push(s,operater2 - operater1);
				break;
			case '*':
				Pop(s,&operater1);
				Pop(s,&operater2);
				Push(s,operater1 * operater2);
				break;
			case '/':
				Pop(s,&operater1);
				Pop(s,&operater2);
				Push(s,operater2 / operater1);
				break;
		}
		scanf("%c", &c);
	}

	Pop(s,&result);
	printf("The result of RPN is %f\n",result);
}

//test;
Status ShowStack(Stack s){
	while(s->base != s->top){
		printf("%f ",*(--(s->top)));
	}
	printf("\n");
}
Status Test(){
	Stack s1;
	InitStack(s1);
	Push(s1,1);
	Push(s1,2);
	Push(s1,3);
	ShowStack(s1);
}
int main(){
	RPT();

	Stack s;
	InitStack(s);
	Push(s,1);
	Push(s,2);
	Push(s,3);
	ShowStack(s);
	return 0;
}