发布时间:2022-08-19 11:34
基于标准C++的计算器实现。
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。
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
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
};
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,
};
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; }
}
//绝对值符号个数的奇偶性
enum ABS_ODEVITY {
ABS_ODD = 1,
ABS_EVEN = 2,
};
//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');
}
}
}
}
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();
}
}
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();
}
}
//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;
}
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;
}
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