逆波兰表达式 转换和计算 C++实现

/*
* File name  : LinkList.cpp
* Function   : 逆波兰表达式 转换和计算 的C++实现
中缀表达式转化为 后缀表达式:
1. 数字直接输出
2.左括号直接进栈
3.右括号直接出栈, 至遇到左括号( 左括号最后也需要出栈)
4. + - * / 若栈顶是左括号,直接入栈
			否则, 优先级低于栈顶符号,持续出栈,最后入栈.;
			      优先级 大于等于栈顶符号,入栈

逆波兰表达式 计算:
1. 数字入栈
2. 遇到符号,出栈两个数字,运算结果入栈.

* Created on : 2016年4月22日
* Author     : [email protected]
* Copyright  : 欢迎大家和我一起交流学习，转载请保持源文件的完整性。
任何单位和个人不经本人允许不得用于商业用途
*/
#include <cstdio>
#include <iostream>

using namespace std;

typedef char Data_t;

typedef struct node {
	Data_t data;
	struct node * next;
}Node, *pNode;

typedef struct {
	pNode ptop;
	int count;
}Lstack;

void Lstack_init(Lstack &LS);
void Lstack_push(Lstack &LS, Data_t elem);
bool Lstack_pop(Lstack &LS, Data_t &elem);
bool Lstack_is_empty(Lstack &LS);
int  Lstack_get_length(Lstack &LS);
bool Lstack_get_elem(Lstack &LS, Data_t &elem);

int get_priority(char c);

int priority_cmp(char x, char y);
void transfer_to_after(char * str , char * one);


int calc(char a, char b, char operate);
int get_rpn_value(char * str);

int main(int argc, char** argv)
{
	char elem='\0';
	int k = 0;
	char *str = "2+(2+1)*2-3";
	char target[20]="\0";
	cout << "9=" << '9' << endl;
	Lstack ls;
	Lstack_init(ls);
	cout << "original string is : " << str << endl;
	char *p = str;
	transfer_to_after(str, target);
	cout << "Target is: " << target << endl;

	cout << "value is " << get_rpn_value(target) << endl;
	return 0;
}

int calc(char a, char b, char operate)
{
	int ret = 0;
	int x = a - 48, y=b-48;
	switch (operate) {
	case '+' :
		ret = x + y;
		break;
	case '-':
		ret = x - y;
		break;
	case '*':
		ret = x * y;
		break;
	case '/':
		if (x == 0)
			cout << "fault, no meanning" << endl;
		ret = x + y;
		break;
	default:
		break;
	}

	return ret;
}

int get_rpn_value(char * str)
{
	Lstack ls;
	Lstack_init(ls);
	char a;
	char b;
	char c;
	int tmp;
	char *p = str;

	while (*p != '\0') {
		switch (*p) {
		case '+':
		case '-':
		case '*':
		case '/':
			Lstack_pop(ls, b);
			Lstack_pop(ls, a);
			tmp=calc(a, b, *p);
			c = tmp + 48;
			Lstack_push(ls,c);
			break;
		default:
			Lstack_push(ls, *p);
			break;
		}
		p++;
	}
	Lstack_pop(ls, c);
	return c-48;
}
void transfer_to_after(char * str, char * one)
{
	Lstack ls; 
	Lstack_init(ls);
	char *p = str;
	int k = 0;
	char tmp;

	while (*p != '\0') {
		switch (*p) {
		case '(' :
			Lstack_push(ls, *p);
			p++;
			break;
		case ')':

			Lstack_get_elem(ls, tmp);

			while (tmp != '(') {
				Lstack_pop(ls, tmp);
				one[k++] = tmp;
				Lstack_get_elem(ls, tmp);
			}
			Lstack_pop(ls, tmp);
			p++;
			break;
		case '+':
		case '-':
		case '*':
		case '/':

			Lstack_get_elem(ls, tmp);
			if (tmp == '(') {
				Lstack_push(ls, *p);
			}
			else {
				while( priority_cmp(*p, tmp) < 0) {
					Lstack_pop(ls, tmp);
					one[k++] = tmp;
					Lstack_get_elem(ls, tmp);
				}
				Lstack_push(ls, *p);
			}
				
			p++;
			break;
		default:
			one[k++] = *p;
			p++;
			break;
		}

	}

	while (Lstack_is_empty(ls) != true) {
		char tmp;
		Lstack_pop(ls, tmp);
		one[k++] = tmp;
	}
}

int get_priority(char c)
{
	switch (c) {
	case '+':
	case '-':
		return 1;
		break;
	case '*':
	case '/':
		return 2;
		break;
	case '(':
	case ')':
		return 3;
		break;
	default:
		return 0;
		break:
	}

}
int priority_cmp(char x, char y)
{
	return (get_priority(x) - get_priority(y));
}



void Lstack_init(Lstack &LS)
{
	LS.count = 0;
	LS.ptop = nullptr;
}

void Lstack_push(Lstack &LS, Data_t elem) {
	pNode p = LS.ptop;
	pNode ptmp = nullptr;

	ptmp = new Node;
	ptmp->data = elem;

	ptmp->next = p;
	LS.ptop = ptmp;
	LS.count++;
}

bool Lstack_pop(Lstack &LS, Data_t &elem) {
	pNode p = LS.ptop;
	pNode ptmp = nullptr;
	if (LS.count == 0) {
		cout << "Lstack is empty,can not pop." << endl;
		elem = -1;
		return false;
	}
	ptmp = LS.ptop;
	elem = LS.ptop->data;

	LS.ptop = ptmp->next;
	delete ptmp;
	LS.count--;

	return true;
}

bool Lstack_is_empty(Lstack &LS) {
	return (LS.count == 0) ? true : false;
}

int Lstack_get_length(Lstack &LS) {
	return LS.count;
}

bool Lstack_get_elem(Lstack &LS, Data_t &elem) {
	if (Lstack_is_empty(LS)) {
		cout << "Lstack is empty." << endl;
		return false;
	}
	elem = LS.ptop->data;
	return true;
}