C++计算器实现 ——(完整功能实现、设计分析)

基于标准C++的计算器实现。

一、需求实现

1、实现功能:

支持运算符:+, - , *, /, %(百分号), ^(幂次方), | |(绝对值),!(阶乘)。其他符号:( ) [ ] { }

支持数据类型:正负数、小数。

2、实现方法

符号优先级处理方法:符号等级制

运算表达式处理方法:后缀表达式法

后缀表达式转换及计算辅助方法:符号栈、数字栈

二、设计实现

总体设计:

计算器类

//计算器类
class Calculator
{
public:
	Calculator();
	void getFormat();					//表达式自定义标准格式化
	int getPrior(char c);				//获取算术符号优先级
	void getPostfix();					//后缀表达式转换
	void calResult();					//计算结果
	void calculate();					//计算方法
	double getResult();					//获取结果

	string operatorSym;					//运算符号
	string infix;						//表达式缓存

private:
	vector<string> postfix;				//后缀表达式向量
	stack<char> symStack;				//符号栈
	stack<double> figStack;				//数字栈
	string stdInfix;					//自定义标准格式化表达式
	double result;						//最终计算结果
};

1、运算优先级功能实现

(1)运算符等级

声明为枚举常量(在整个类中恒定),便于数据管理、数据与程序分离。

//算术符号优先权等级
enum PRIO_LV {
	PRIO_LV0 = 0,
	PRIO_LV1 = 1,
	PRIO_LV2 = 2,
	PRIO_LV3 = 3,
	PRIO_LV4 = 4,
};
(2)运算符优先级获取

用于运算优先级比较的依据。

//获取算术符号优先级
int Calculator::getPrior(char c) {

	if (c == '+' || c == '-') {
		return PRIO_LV1;
	}
	else if (c == '*' || c == '/') {
		return PRIO_LV2;
	}
	else if (c == '%' || c == '^') {
		return PRIO_LV3;
	}
	else if (c == '!') {
		return PRIO_LV4;
	}
	else {
		return PRIO_LV0;
	}
	//else { cout << c << 非法符号! << endl; }
}

2、绝对值符号奇偶性实现

//绝对值符号个数的奇偶性
enum ABS_ODEVITY {
	ABS_ODD = 1,
	ABS_EVEN = 2,
};

3、正负数运算实现


//表达式自定义标准格式化
void Calculator::getFormat() {

	stdInfix = infix;

	//实现正负数
	//for (int i = 0; i < stdInfix.length(); i++) {			//string下标调用运算符时可能会导致类型溢出
	for (size_t i = 0; i < stdInfix.size(); i++) {			//string.size()返回size_type类型,避免下标运算时的类型溢出
		if (stdInfix[i] == '-' || stdInfix[i] == '+') {		//-x转换为0-x,+x转化为0+x
			if (i == 0) {
				stdInfix.insert(0, 1, '0');
			}
			else if (stdInfix[i - 1] == '(') {
				stdInfix.insert(i, 1, '0');
			}
		}
	}
}

4、后缀表达式转换

要直接对表达式求值,首先要能够正确解释表达式,或者翻译成能正确求值的一个机器指令序列,以便计算机的处理执行。因此有前缀表达式和后缀表达式方法,此处采用较为广泛的后缀表达式方法。

//后缀表达式转换
void Calculator::getPostfix() {

	int absNumeber = ABS_ODD;				//绝对值符号个数的奇偶性
	string tmp;

	//for (int i = 0; i < stdInfix.length(); i++) {
	for (size_t i = 0; i < stdInfix.size(); i++) {					//string.size()返回size_type类型,避免下标运算时的类型溢出
		tmp = "";
		switch (stdInfix[i]) {
		case '+':
		case '-':
		case '*':
		case '/':
		case '%':
		case '^':
		case '!':
			if (symStack.empty() || symStack.top() == '(' || symStack.top() == '[' || symStack.top() == '{' || (symStack.top() == '|' && absNumeber == ABS_ODD)) {
				symStack.push(stdInfix[i]);
			}
			else {
				while (!symStack.empty() && (getPrior(symStack.top()) >= getPrior(stdInfix[i]))) {
					tmp += symStack.top();
					postfix.push_back(tmp);
					symStack.pop();
					tmp = "";
				}
				symStack.push(stdInfix[i]);
			}
			break;
		case '|':
			if (absNumeber == ABS_ODD) {
				symStack.push(stdInfix[i]);
				absNumeber = ABS_EVEN;
			}
			else{
				while (!symStack.empty() && symStack.top() != '|') {
					tmp += symStack.top();
					postfix.push_back(tmp);
					symStack.pop();
					tmp = "";
				}
				if (!symStack.empty() && symStack.top() == '|') {
					tmp += symStack.top();
					postfix.push_back(tmp);						//左绝对值符号'|'加入后缀表达式,用于绝对值的检测计算
					symStack.pop();
					absNumeber = ABS_ODD;
				}
			}
			break;
		case '(':
		case '[':
		case '{':
			symStack.push(stdInfix[i]);
			break;
		case ')':
			while (!symStack.empty() && symStack.top() != '(') {
				tmp += symStack.top();
				postfix.push_back(tmp);
				symStack.pop();
				tmp = "";
			}
			if (!symStack.empty() && symStack.top() == '(') {
				symStack.pop();							//将左括号出栈丢弃
			}
			break;
		case ']':
			while (!symStack.empty() && symStack.top() != '[') {
				tmp += symStack.top();
				postfix.push_back(tmp);
				symStack.pop();
				tmp = "";
			}
			if (!symStack.empty() && symStack.top() == '[') {
				symStack.pop();							//将左括号出栈丢弃
			}
			break;
		case '}':
			while (!symStack.empty() && symStack.top() != '{') {
				tmp += symStack.top();
				postfix.push_back(tmp);
				symStack.pop();
				tmp = "";
			}
			if (!symStack.empty() && symStack.top() == '{') {
				symStack.pop();							//将左括号出栈丢弃
			}
			break;
		default:
			if ((stdInfix[i] >= '0' && stdInfix[i] <= '9')) {
				tmp += stdInfix[i];
				while (i + 1 < stdInfix.length() && (stdInfix[i + 1] >= '0' && stdInfix[i + 1] <= '9' || stdInfix[i + 1] == '.')) {		//小数处理

					tmp += stdInfix[i + 1];			//是连续的数字,则追加
					i++;
				}
				if (tmp[tmp.length() - 1] == '.') {
					tmp += '0';						//将x.做x.0处理
				}
				postfix.push_back(tmp);
			}
			break;
		}//end switch
	}//end for

	//if(!symStack.empty()) {
	while (!symStack.empty()) {						//将栈中剩余符号加入后缀表达式
		tmp = "";
		tmp += symStack.top();
		postfix.push_back(tmp);
		symStack.pop();
	}
}

5、计算后缀表达式

计算后缀表达式,得到最终计算结果,将结果传递到计算器类的result属性。

//计算
void Calculator::calResult() {

	string tmp;
	double number = 0;
	double op1 = 0, op2 = 0;

	for (int i = 0; i < postfix.size(); i++) {
		tmp = postfix[i];
		if (tmp[0] >= '0' && tmp[0] <= '9') {
			number = atof(tmp.c_str());
			figStack.push(number);
		}
		else if (postfix[i] == "+") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(op1 + op2);
		}
		else if (postfix[i] == "-") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(op1 - op2);
		}
		else if (postfix[i] == "*") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(op1* op2);
		}
		else if (postfix[i] == "/") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop(); 
			}
			if (op2 != 0) {
				///除数不为0,未做处理,默认
			}
			figStack.push(op1 / op2);
		}
		else if (postfix[i] == "%") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(fmod(op1, op2));			//可进行小数求余
		}
		else if (postfix[i] == "^") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(pow(op1, op2));
		}
		else if (postfix[i] == "|") {
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(abs(op1));
		}
		else if (postfix[i] == "!") {
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			if (op1 > 0) {
				//阶乘数应大于;为小数时(转化为整数求阶)
				double factorial = 1;
				for (int i = 1; i <= op1; ++i)
				{
					factorial *= i;
				}
				op1 = factorial;
			}
			figStack.push(op1);
		}
	}//end for
	if (!figStack.empty()) {
		result = figStack.top();
	}
}

6、对象的外部调用方法

//计算方法
void Calculator::calculate() {

	getFormat();				//表达式自定义标准格式化
	getPostfix();				//后缀表达式转换
	calResult();				//获取算术结果
}
//获取结果
double Calculator::getResult() {
	return result;
}

三、完整代码

Calculator.h: 头文件

//Calculator.h: 头文件
#include 
#include 
#include 
using namespace std;

//计算器类
class Calculator
{
public:
	Calculator();
	void getFormat();					//表达式自定义标准格式化
	int getPrior(char c);				//获取算术符号优先级
	void getPostfix();					//后缀表达式转换
	void calResult();					//计算后缀表达式
	void calculate();					//计算方法
	double getResult();					//获取结果

	string operatorSym;					//运算符号
	string infix;						//表达式缓存

private:
	vector<string> postfix;				//后缀表达式向量
	stack<char> symStack;				//符号栈
	stack<double> figStack;				//数字栈
	string stdInfix;					//自定义标准格式化表达式
	double result;						//最终计算结果
};

Calculator.cpp: 实现文件

//Calculator.cpp: 实现文件
#include 
#include 
#include 
#include 
using namespace std;

//绝对值符号个数的奇偶性
enum ABS_ODEVITY {
	ABS_ODD = 1,
	ABS_EVEN = 2,
};

//算术符号优先权等级
enum PRIO_LV {
	PRIO_LV0 = 0,
	PRIO_LV1 = 1,
	PRIO_LV2 = 2,
	PRIO_LV3 = 3,
	PRIO_LV4 = 4,
};

Calculator::Calculator() {				//构造函数,初始化成员变量

	operatorSym = "支持运算符:+, - , *, /, %(百分号), ^(幂次方), | |(绝对值),!(阶乘)。其他符号:( ) [ ] { }";
	result = 0.0;
}


//表达式自定义标准格式化
void Calculator::getFormat() {

	stdInfix = infix;

	//实现正负数
	//for (int i = 0; i < stdInfix.length(); i++) {					//string下标调用运算符时可能会导致类型溢出
	for (size_t i = 0; i < stdInfix.size(); i++) {					//string.size()返回size_type类型,避免下标运算时的类型溢出
		if (stdInfix[i] == '-' || stdInfix[i] == '+') {				//-x转换为0-x,+x转化为0+x
			if (i == 0) {
				stdInfix.insert(0, 1, '0');
			}
			else if (stdInfix[i - 1] == '(') {
				stdInfix.insert(i, 1, '0');
			}
		}
	}
}

//获取算术符号优先级
int Calculator::getPrior(char c) {

	if (c == '+' || c == '-') {
		return PRIO_LV1;
	}
	else if (c == '*' || c == '/') {
		return PRIO_LV2;
	}
	else if (c == '%' || c == '^') {
		return PRIO_LV3;
	}
	else if (c == '!') {
		return PRIO_LV4;
	}
	else {
		return PRIO_LV0;
	}
	//else { cout << c << 非法符号! << endl; }
}

//后缀表达式转换
void Calculator::getPostfix() {

	int absNumeber = ABS_ODD;				//绝对值符号个数的奇偶性
	string tmp;

	//for (int i = 0; i < stdInfix.length(); i++) {
	for (size_t i = 0; i < stdInfix.size(); i++) {					//string.size()返回size_type类型,避免下标运算时的类型溢出
		tmp = "";
		switch (stdInfix[i]) {
		case '+':
		case '-':
		case '*':
		case '/':
		case '%':
		case '^':
		case '!':
			if (symStack.empty() || symStack.top() == '(' || symStack.top() == '[' || symStack.top() == '{' || (symStack.top() == '|' && absNumeber == ABS_ODD)) {
				symStack.push(stdInfix[i]);
			}
			else {
				while (!symStack.empty() && (getPrior(symStack.top()) >= getPrior(stdInfix[i]))) {
					tmp += symStack.top();
					postfix.push_back(tmp);
					symStack.pop();
					tmp = "";
				}
				symStack.push(stdInfix[i]);
			}
			break;
		case '|':
			if (absNumeber == ABS_ODD) {
				symStack.push(stdInfix[i]);
				absNumeber = ABS_EVEN;
			}
			else{
				while (!symStack.empty() && symStack.top() != '|') {
					tmp += symStack.top();
					postfix.push_back(tmp);
					symStack.pop();
					tmp = "";
				}
				if (!symStack.empty() && symStack.top() == '|') {
					tmp += symStack.top();
					postfix.push_back(tmp);						//左绝对值符号'|'加入后缀表达式,用于绝对值的检测计算
					symStack.pop();
					absNumeber = ABS_ODD;
				}
			}
			break;
		case '(':
		case '[':
		case '{':
			symStack.push(stdInfix[i]);
			break;
		case ')':
			while (!symStack.empty() && symStack.top() != '(') {
				tmp += symStack.top();
				postfix.push_back(tmp);
				symStack.pop();
				tmp = "";
			}
			if (!symStack.empty() && symStack.top() == '(') {
				symStack.pop();							//将左括号出栈丢弃
			}
			break;
		case ']':
			while (!symStack.empty() && symStack.top() != '[') {
				tmp += symStack.top();
				postfix.push_back(tmp);
				symStack.pop();
				tmp = "";
			}
			if (!symStack.empty() && symStack.top() == '[') {
				symStack.pop();							//将左括号出栈丢弃
			}
			break;
		case '}':
			while (!symStack.empty() && symStack.top() != '{') {
				tmp += symStack.top();
				postfix.push_back(tmp);
				symStack.pop();
				tmp = "";
			}
			if (!symStack.empty() && symStack.top() == '{') {
				symStack.pop();							//将左括号出栈丢弃
			}
			break;
		default:
			if ((stdInfix[i] >= '0' && stdInfix[i] <= '9')) {
				tmp += stdInfix[i];
				while (i + 1 < stdInfix.length() && (stdInfix[i + 1] >= '0' && stdInfix[i + 1] <= '9' || stdInfix[i + 1] == '.')) {		//小数处理

					tmp += stdInfix[i + 1];			//是连续的数字,则追加
					i++;
				}
				if (tmp[tmp.length() - 1] == '.') {
					tmp += '0';						//将x.做x.0处理
				}
				postfix.push_back(tmp);
			}
			break;
		}//end switch
	}//end for

	//if(!symStack.empty()) {
	while (!symStack.empty()) {						//将栈中剩余符号加入后缀表达式
		tmp = "";
		tmp += symStack.top();
		postfix.push_back(tmp);
		symStack.pop();
	}
}

//计算后缀表达式
void Calculator::calResult() {

	string tmp;
	double number = 0;
	double op1 = 0, op2 = 0;

	for (int i = 0; i < postfix.size(); i++) {
		tmp = postfix[i];
		if (tmp[0] >= '0' && tmp[0] <= '9') {
			number = atof(tmp.c_str());
			figStack.push(number);
		}
		else if (postfix[i] == "+") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(op1 + op2);
		}
		else if (postfix[i] == "-") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(op1 - op2);
		}
		else if (postfix[i] == "*") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(op1* op2);
		}
		else if (postfix[i] == "/") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop(); 
			}
			if (op2 != 0) {
				///除数不为0,未做处理,默认
			}
			figStack.push(op1 / op2);
		}
		else if (postfix[i] == "%") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(fmod(op1, op2));			//可进行小数求余
		}
		else if (postfix[i] == "^") {
			if (!figStack.empty()) {
				op2 = figStack.top();
				figStack.pop();
			}
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(pow(op1, op2));
		}
		else if (postfix[i] == "|") {
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			figStack.push(abs(op1));
		}
		else if (postfix[i] == "!") {
			if (!figStack.empty()) {
				op1 = figStack.top();
				figStack.pop();
			}
			if (op1 > 0) {
				//阶乘数应大于;为小数时(转化为整数求阶)
				double factorial = 1;
				for (int i = 1; i <= op1; ++i)
				{
					factorial *= i;
				}
				op1 = factorial;
			}
			figStack.push(op1);
		}
	}//end for
	if (!figStack.empty()) {
		result = figStack.top();
	}
}

//计算方法
void Calculator::calculate() {

	getFormat();				//表达式自定义标准格式化
	getPostfix();				//后缀表达式转换
	calResult();				//获取算术结果
}

//获取结果
double Calculator::getResult() {
	return result;
}

Main.cpp:主程序

#include 
using namespace std;

//const int MAX_EXP_LEN = 1000;			//最大表达式长度	防止内存溢出

//main函数
int main()
{
	Calculator cal;
	cout << cal.operatorSym << endl;
	cout << "----------" << endl;

	while (true) {
		getline(cin, cal.infix);
		/*
		if (cal.infix.length() > MAX_EXP_LEN) {
			cout << "超出最大长度!" << endl;
			system("pause");
		}
		else {
			cal.calculate();
		}
		*/
		cal.calculate();
		cout << cal.getResult() << endl;
	}
	return 0;
}

资源获取

  • 计算器整体项目打包 及 项目设计说明书(含总结) csdn下载地址:Calculator.rar

  • 百度网盘链接: https://pan.baidu.com/s/19uDZHTOITeStOaUZdgIy8Q 提取码: xyda

  • 另基于此程序的mfc计算器(用户界面)实现,请转文章 mfc计算器实现

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