C/C++中数据类型转换详解及其作用介绍

int main() {
    int a = 6; 
    a  = a + 3.5; 
    cout << a << endl;

    return 0;
}

int main() {
    int a = int(2.3);
    double b = double(12);
    cout << a << endl;
    cout << b << endl;

    return 0;
}

#ifndef PROJECT8_COMPLEX_H
#define PROJECT8_COMPLEX_H

#include <iOStream>
using namespace std;

class Complex {
private:
    double real;
    double imaginary;
public:
    Complex() {};  // 无参构造
    Complex(double r, double i) : real(r), imaginary(i) {};  // 有参构造
    Complex(Complex & c) {  // 复制构造函数
        cout << "copy constructor" << endl;
    };
    Complex(double r) : real(r) {};  // 转换构造函数
    };
};

#endif //PROJECT8_COMPLEX_H

#ifndef PROJECT8_COMPLEX_H
#define PROJECT8_COMPLEX_H

#include <iostream>
using namespace std;

class Complex {
public:
    double real;
    double imaginary;
public:
    Complex() {};  // 无参构造
    Complex(double r, double i) : real(r), imaginary(i) {};  // 有参构造
    Complex(double r) : real(r) {};  // 转换构造函数
    operator double() {return real;};  // 类型转换函数
    Complex operator+(Complex &c) {
        return Complex(real + c.real, imaginary + c.imaginary);
    };
};

#endif //PROJECT8_COMPLEX_H

#include <iostream>
#include "Complex.h"
using namespace std;

int main() {
    Complex c1(3.1, 4), c2(5.2, -10);
    double d1, d2;
    d1 = c1 + 2;  // 3.1 + 2, 调用类型展缓函数
    cout << d1 << endl;
    d2 = c1 + c2;  // 3.1 + 5.2, 调用类型展缓函数
    cout << d2 << endl;

    return 0;
}