C++ 有关赋值构造函数 拷贝构造函数 自动型别转换

#include <iostream>using namespace std;class T{private:int num;public:T():num(0) {cout << "In T(): num = " << num << endl;}T(int size):num(size) {cout << "In T(int): num = " << num << endl; }T(const T &t) {cout << "In T(const T &)" << endl;}void setNum(int num) {this->num = num;}~T() {cout << "In ~T():num = " << num << endl; }T &operator = (const T &t) {cout << "In =" << endl;}};void f(T t) {cout << "In f" << endl;};int main(){f(10);       //调用 T(int size)构造函数生成一个对象，这个对象在f函数结束时调用析构函数释放 T t;//调用 T()构造函数 t = 40;//先通过40自动型别转换调用T(int size)生成一个临时对象，然后调用T &operator = (const T &t)赋值构造函数，然后临时对象释放调用析构函数 t.setNum(12);T s = 88;//通过自动型别转换 用T(int size)生成s对象 cout << "aaaa" << endl;return 0;//调用s的析构函数，然后调用t的析构函数 }

输出：

In T(int): num = 10
In f
In ~T():num = 10
In T(): num = 0
In T(int): num = 40
In =
In ~T():num = 40
In T(int): num = 88
aaaa
In ~T():num = 88
In ~T():num = 12