c++ 数据结构 *** 栈的应用——计算器

新年第一次发，这几天在复习期末考试。。但是好像已经复习完了但是还有十天多才考试感觉挺无聊的就写个计算器。。但是代码太难看。。代码里一堆的if else。。我还是学好catch throw吧！！！！先贴出来。。看看再修修补补，好好弄弄结构。。。买了明晚星战的票。。那今晚要不要出去high呢。。。。。。

#pragma once
#ifndef CALCULATOR_H
#define CALCULATOR_H

#include<iostream>
#include<string>
#include<vector>

using namespace std;

class Expression {
private:
	string preExpression;//一次性读取表达式，用字符串存
	stack<char> operators;//记录表达式中的操作符
	stack<double> operand;//记录表达式中的操作数
	int loc;//记录读取到preExpression的第几个位置了
	int length;//记录preExpression的长度
	char ch;//记录当前读取到的preExpression的字符
	bool sign;//记录loc是否读取到preExpression的最后一个字符,1为未读取到最后一个字符，0为读取到最后一个字符

	//start辅助函数
	void show();//提醒输入表达式，并存入preExpression中
	void operating();//开始进行计算过程
	int isOperator(char ch);//判断ch是否是操作符，返回0说明是数字，返回1说明是操作符，返回2说明非法符号
	double readOpend();//读取操作数
	int opera(char ch,char top);//读取操作符，返回0说明操作正常，返回1说明除法有问题，返回2说明表达式出错,3说明表达式不合法
	bool compareOpe(char ch, char top);//判断操作符的优先级

public:
	void start();//开始程序
};

void Expression::show() {//提醒输入表达式，并存入preExpression中
	cout << "Enter an arithmetic expression:\nExample:(((2+3)*5-7)/15)*34=\n";
	cout << "quit to quit" << endl;
	cin >> preExpression;
	if (preExpression == "quit") {
		cout << "Bye!" << endl;
		system("pause");
		exit(1);
	}
	length = preExpression.length();
	loc = 0;
	sign = 0;
}

void Expression::operating() {//开始进行计算过程
	operators.push('=');//设置栈顶标志
	while (!operators.empty()) {
		if (!sign) {
			ch = preExpression[loc];
			//判断ch
			if (isOperator(ch) == 3) { //如果ch不是操作数也不是操作符
				cout << "Sorry,expressions containing illegal characters." << endl;
				cout << "Please re-enter!" << endl;
				cout << endl;
				return;
			}
			else if (ch == '='&&loc != length - 1) {//=符号出现在中间
				cout << "\'=\' couldn't in the middle of arithmetic expression!" << endl;
				cout << "Please re-enter!" << endl;
				cout << endl;
				return;
			}
			else if (isOperator(ch)) {//如果ch是操作符
				if (operators.empty()) {
					cout << "There may hava some errors!" << endl;
					cout << "Bye!" << endl;
					system("pause");
					exit(1);
				}
				char top = operators.top();
				operators.pop();
				int wrong;
				wrong = opera(ch, top);
				++loc;
				if (loc == length)sign = 1;
				if (wrong == 1) {
					cout << "Divisor can not be zero!" << endl;
					cout << "Please re-enter!" << endl;
					cout << endl;
					return;
				}
				else if (wrong == 2) {
					cout << this->preExpression << " is not an arithmetic expression!" << endl;
					cout << "Please re-enter!" << endl;
					cout << endl;
					return;
				}
				else if (wrong == 3) {
					if (operand.empty()) {
						cout << "Sorry,expressions doesn't illegal." << endl;
						cout << "Please re-enter!" << endl;
						cout << endl;
						return;
					}
					double opend = operand.top();
					if (operand.empty()) {
						cout << "Sorry,expressions doesn't illegal." << endl;
						cout << "Please re-enter!" << endl;
						cout << endl;
						return;
					}
					else {
						cout << "The result is " << opend << endl;
						cout << endl;
						return;
					}
				}
			}
			else {//如果ch是操作数
				double opend = readOpend();
				operand.push(opend);
			}
		}
		else {
			if (operators.empty()) {
				cout << "There may hava some errors!" << endl;
				cout << "Bye!" << endl;
				system("pause");
				exit(1);
			}
			operators.pop();
			if (operators.empty()) {
				cout << "There may hava some errors!" << endl;
				cout << "Bye!" << endl;
				system("pause");
				exit(1);
			}
			char top = operators.top();
			operators.pop();
			int wrong;
			wrong = opera(ch, top);
			if (wrong == 1) {
				cout << "Divisor can not be zero!" << endl;
				cout << "Please re-enter!" << endl;
				cout << endl;
				return;
			}
			else if (wrong == 2) {
				cout << this->preExpression << " is not an arithmetic expression!" << endl;
				cout << "Please re-enter!" << endl;
				cout << endl;
				return;
			}
			else if (wrong == 3) {
				if (operand.empty()) {
					cout << "Sorry,expressions doesn't illegal." << endl;
					cout << "Please re-enter!" << endl;
					cout << endl;
					return;
				}
				double opend = operand.top();
				operand.pop();
				if (!operand.empty()) {
					cout << "Sorry,expressions doesn't illegal." << endl;
					cout << "Please re-enter!" << endl;
					cout << endl;
					return;
				}
				else {
					cout << "The result is " << opend << endl;
					cout << endl;
					return;
				}

			}
		}
	}
}
int Expression::isOperator(char ch) {//判断是否是操作符
	if ((ch >= '0'&&ch <= '9')||ch=='.')
		return 0;
	else if (ch == '+' || ch == '-' || ch == '*' || ch == '/' || ch == '='||ch=='('||ch==')')
		return 1;
	else return 3;
}

double Expression::readOpend() {//读取操作数

	//开始读取整数部分
	double opend = 0;
	double opendInte = 0, opendDeci = 0;//整数部分与小数部分
	while (ch >= '0'&&ch <= '9'&&!sign) {
		opendInte = opendInte * 10 + ch - '0';
		++loc;
		if (loc == length)sign = 1;
		else ch = preExpression[loc];
	}
	//如果下一个不是0-9的字符而是小数点，那么开始读取小数部分
	if (ch == '.') {
		++loc;
		ch = preExpression[loc];
		int rank = 10;
		while (ch >= '0'&&ch <= '9'&&!sign) {
			opendDeci = opendDeci + (ch - '0')*1.0 / rank;
			rank *= 10;
			++loc;
			if (loc == length)sign = 1;
			else ch = preExpression[loc];
		}
	}
	opend = opendInte + opendDeci;
	return opend;
}

int Expression::opera(char ch,char top) {//读取操作符
	if (ch == '='&&top == '=') {
		return 3;
	}
	else {
		if (!compareOpe(ch, top)) {//如果ch的优先级比top高
			operators.push(top);
			operators.push(ch);
		}
		else {//如果ch的优先级比top低或者相等
			double A, B;
			if (!operand.empty())//弹出操作数A
				A = operand.top();
			else return 2;
			operand.pop();
			if (!operand.empty())//弹出操作数B
				B = operand.top();
			else return 2;
			operand.pop();

			if (top == '+')
				operand.push(A + B);
			else if (top == '-')
				operand.push(B-A);
			else if (top == '*')
				operand.push(A*B);
			else if (top == '/') {
				if (A == 0) return 1;
				else operand.push(B / A);
			}
			if (ch == ')') {//判断ch是否为')'
				top = operators.top();
				operators.pop();
				while (top != '('&&!operators.empty()) {
					double A, B;
					if (!operand.empty())//弹出操作数A
						A = operand.top();
					else return 2;
					operand.pop();
					if (!operand.empty())//弹出操作数B
						B = operand.top();
					else return 2;
					operand.pop();

					if (top == '+')
						operand.push(A + B);
					else if (top == '-')
						operand.push(B - A);
					else if (top == '*')
						operand.push(A*B);
					else if (top == '/') {
						if (A == 0) return 1;
						else operand.push(B / A);
					}
					top = operators.top();
					operators.pop();
				}
				if (operators.empty())return 2;
			}
			else {
				operators.push(ch);
			}
		}
	}
}

bool Expression::compareOpe(char ch, char top) {//判断操作符的优先级

	if (ch == '='||ch==')')return true;

	else if (ch == '(')return false;//ch==(

	else if (ch == '+' || ch == '-') {//ch==+||ch==-,只有top==+,-,*,/
		if (top == '('||top=='=')return false;
		else return true;
	}

	else if (ch == '*' || ch == '/') {//ch==*||ch==/,只有top==*,/
		if (top == '*' || top == '/')return true;
		else return false;
	}
}

void Expression::start() {

	show();
	operating();
}
#endif

test：

#include<iostream>
#include<cmath>
#include<queue>
#include<stack>
#include<map>
#include<set>
#include<string>
#include<vector>
#include"Calculator.h"

using namespace std;

int main(){
	string preExpression;
	while (1) {
			Expression expression;
			expression.start();
	}
	return 0;
}