复数的加减运算（c++）

在C++中，复数可以使用结构体或者类来表示。以下是使用结构体实现复数加减运算的示例代码：

#include <iostream>
using namespace std;

struct Complex {
    double real;
    double imag;
};

Complex add(Complex c1, Complex c2) {
    Complex result;
    result.real = c1.real + c2.real;
    result.imag = c1.imag + c2.imag;
    return result;
}

Complex sub(Complex c1, Complex c2) {
    Complex result;
    result.real = c1.real - c2.real;
    result.imag = c1.imag - c2.imag;
    return result;
}

int main() {
    Complex c1, c2, res;
    cout << "Enter the real and imaginary parts of first complex number: ";
    cin >> c1.real >> c1.imag;
    cout << "Enter the real and imaginary parts of second complex number: ";
    cin >> c2.real >> c2.imag;
    res = add(c1, c2);
    cout << "Addition: " << res.real << " + " << res.imag << "i" << endl;
    res = sub(c1, c2);
    cout << "Subtraction: " << res.real << " + " << res.imag << "i" << endl;
    return 0;
}

在上面的代码中，我们定义了一个复数结构体`Complex`，并实现了两个函数`add`和`sub`，分别用于计算复数的加法和减法。在`main`函数中，我们通过用户输入两个复数，调用`add`和`sub`函数进行计算，并输出结果。

另外，如果使用类来实现复数，可以将加法和减法运算符重载，使得代码更加简洁易读。以下是使用类实现复数加减运算的示例代码：

#include <iostream>
using namespace std;

class Complex {
public:
    Complex(double r = 0, double i = 0) : real(r), imag(i) {}
    Complex operator+(Complex c2) {
        return Complex(real + c2.real, imag + c2.imag);
    }
    Complex operator-(Complex c2) {
        return Complex(real - c2.real, imag - c2.imag);
    }
    friend ostream& operator<<(ostream& os, Complex c) {
        os << c.real << " + " << c.imag << "i";
        return os;
    }
private:
    double real;
    double imag;
};

int main() {
    Complex c1, c2, res;
    cout << "Enter the real and imaginary parts of first complex number: ";
    cin >> c1;
    cout << "Enter the real and imaginary parts of second complex number: ";
    cin >> c2;
    res = c1 + c2;
    cout << "Addition: " << res << endl;
    res = c1 - c2;
    cout << "Subtraction: " << res << endl;
    return 0;
}

在上面的代码中，我们定义了一个复数类`Complex`，其中重载了加法和减法运算符，并定义了一个友元函数重载输出运算符。在`main`函数中，我们通过用户输入两个复数，直接使用重载的运算符进行计算，并输出结果。