c++實現簡單計算器

幫一個同學寫的，非計算機類專業，應付交差，也沒什么功能，兩個數的加減乘除運算，以及三角函數的運算。要求用到模板、運算符重載和異常處理。

一直以來都是用的java，沒怎么用過c++，就當是復習了一下c++語法。

 

代碼如下：

#include<iostream>
#include<string>
#include<cmath>
#include<cstdlib>

using namespace std;

//四則運算
template <class T> class ElementaryArithmetic{
private:
    T result;
    T operand1, operand2;
    char operators;
public:
    //四則運算
    void Calculate(); 
    //加法運算
    void add(T, T); 
    //減法運算
    void subtraction(T, T); 
    //乘法運算
    void multiplication(T, T);
    //除法運算
    void divide(T, T); 
    //輸出運算符重載
    template <class E> friend ostream &operator<<(ostream&, ElementaryArithmetic<E> &);
};

//四則運算
template <class T> void ElementaryArithmetic<T>::Calculate(){
    int type;

loop1:
    system("cls");
    cout << endl << "*******************" << endl;
    cout << "*   1.加法運算    *" << endl; 
    cout << "*   2.減法運算    *" << endl;  
    cout << "*   3.乘法運算    *" << endl;  
    cout << "*   4.除法運算    *" << endl; 
    cout << "*******************" << endl << endl;
    cout << "請輸入菜單項(1-4)：";
    try{
        cin >> type;
        if (type != 1 && type != 2 && type != 3 && type != 4)
            throw 1;
    }
    catch (int e){
        cout << endl << "輸入錯誤，請重新輸入選項...";
        system("pause");
        goto loop1;
    }
    
    cout << endl << "請輸入兩個數字：";
    cin >> operand1 >> operand2;
    if (type == 1){
        add(operand1, operand2);
        operators = '+';
    }
    else if (type == 2){
        subtraction(operand1, operand2);
        operators = '-';
    }
    else if (type == 3){
        multiplication(operand1, operand2);
        operators = '*';
    }
    else if (type == 4){
        divide(operand1, operand2);
        operators = '/';
    }
    
}

//加法運算
template <class T> void ElementaryArithmetic<T>::add(T operand1,T operand2){
    result = operand1 + operand2;
}

//減法運算
template <class T> void ElementaryArithmetic<T>::subtraction(T operand1, T operand2){
    result = operand1 - operand2;
}

//乘法運算
template <class T> void ElementaryArithmetic<T>::multiplication(T operand1, T operand2){
    result = operand1 * operand2;
}

//除法運算
template <class T> void ElementaryArithmetic<T>::divide(T operand1, T operand2){
    try{
        //除數為0，出現異常
        if ((operand2 - 0) < 1e-8 && (operand2 - 0) > -1e-8)
            throw 0;
    }
    catch (int){
        throw ;
    }
    result = operand1 / operand2;
}

//輸出運算符重載
template <class E> ostream& operator<<(ostream &os, ElementaryArithmetic<E> &result){
    os << endl << "計算結果 ： " << result.operand1 << result.operators << result.operand2 << '=' << result.result << endl;
    return os;
}

//三角函數
class Trigonometric{
private:
    double radian;
    string type;
    double result;
public:
    //三角函數計算
    void Calculate();
    //輸出運算符重載
    friend ostream &operator<<(ostream&, Trigonometric &);
};

//三角函數計算
void Trigonometric::Calculate(){
    int option;

loop2:
    system("cls");
    cout << "*******************" << endl;
    cout << "*    1.求正弦      *"<< endl; 
    cout << "*    2.求余弦      *"<< endl;
    cout << "*    3.求正切      *"<< endl;
    cout << "*******************" << endl << endl;
    cout << "請輸入菜單項(1-3)：";
    try{
        cin >> option;
        if (option != 1 && option != 2 && option != 3 && option != 4)
            throw 2;
    }
    catch (int e){
        cout << endl << "輸入錯誤，請重新輸入選項..." ;
        system("pause");
        goto loop2;
    }
    

    cout << endl << "請輸入弧度：";
    cin >> radian;

    if (option == 1){
        result = sin(radian);
        type = "sin";
    }
    else if (option == 2){
        result = cos(radian);
        type = "cos";
    }
    else if (option == 3){
        result = tan(radian);
        type = "tan";
    }
}

//輸出運算符重載
ostream &operator<<(ostream &os, Trigonometric &result){
    os << endl << "計算結果 ： " << result.type << "(" << result.radian << ") = " << result.result << endl;
    return os;
}

int main(){
    int type;

loop:
    while (true){
        system("cls");
        cout << "*******主菜單**********" << endl;
        cout << "*                     *" << endl;
        cout << "*   1. 四則運算       *" << endl;
        cout << "*   2. 三角函數       *" << endl;
        cout << "*   3. 退出程序       *" << endl;
        cout << "*                     *" << endl;
        cout << "***********************" << endl << endl;
        cout << "請輸入菜單項(1-3)：";

        try{
            cin >> type;
            if (type != 1 && type != 2 && type != 3)
                throw - 1;
        
            if (type == 1){
                ElementaryArithmetic<double> calc;
                calc.Calculate();
                cout << calc;
            }
            else if (type == 2){
                Trigonometric calc;
                calc.Calculate();
                cout << calc;
            }
            else if (type == 3)
                break;
        }
        catch (int e){
            if (e == -1){
                cout << endl << "輸入錯誤，請重新輸入選項...";
                system("pause");
                goto loop;
            }
            else if (e == 0)
                cout << "除數不能為 0 " << endl;
            
        }
        cout << endl;
        system("pause");
    }
    return 0;
}

 

好吧，其實我也不知道為什么要求用模板和運算符重載，感覺沒什么必要，典型的作業代碼，不過也可能是我思想的局限性。總之，就這樣吧。