#include<iostream> using namespace std; class Complex{ public: Complex(double r=0,double i=0):real(r),imga(i){ } friend Complex operator + (const Complex &c1,const Complex &c2); friend Complex operator - (Complex c1,Complex c2); friend ostream & operator <<(ostream &out,const Complex &c) private: double real,imga; }; Complex operator + (const Complex &c1,const Complex &c2) const{ return (c1.real + c2.real,c1.imga + c2.imga); } Complex operator - (const Complex &c2) const{ return (c1.real - c2.real,c1.imga - c2.imga); } ostream operator << (ostream &out ,const Complex &c) { out<<"("<<c.real<<","<<c.imga<<")"<<endl; return out; }这段代码有什么问题

这段代码有一些问题：

1. 在 Complex 类中，`operator +` 和 `operator -` 的定义中都使用了 `const` 修饰参数，但是在函数体内却使用了非 const 成员函数 `real` 和 `imga`，这是不合法的。

2. 在 `operator +` 和 `operator -` 的定义中，返回值应该是 `Complex` 类型，而不是使用逗号运算符后返回的结果。

3. 在 `operator -` 的定义中，函数名后的参数应该是 `Complex c1` 而不是 `Complex c2`。

4. 在 `operator <<` 的定义中，函数名后的返回值应该是 `ostream&` 而不是 `ostream`。

下面是修改后的代码：

#include<iostream> 
using namespace std; 

class Complex{ 
public: 
    Complex(double r = 0, double i = 0) : real(r), imga(i) { 
    } 
    friend Complex operator +(const Complex &c1, const Complex &c2); 
    friend Complex operator -(const Complex &c1, const Complex &c2); 
    friend ostream & operator <<(ostream &out, const Complex &c); 
private: 
    double real, imga; 
}; 

Complex operator +(const Complex &c1, const Complex &c2) { 
    return Complex(c1.real + c2.real, c1.imga + c2.imga); 
} 

Complex operator -(const Complex &c1, const Complex &c2) { 
    return Complex(c1.real - c2.real, c1.imga - c2.imga); 
} 

ostream& operator << (ostream &out, const Complex &c) { 
    out << "(" << c.real << "," << c.imga << ")" << endl; 
    return out; 
} 

int main() { 
    Complex a(1, 2), b(3, 4); 
    cout << a + b << endl; 
    cout << a - b << endl; 
    return 0; 
}