我正在学习析构函数、复制和克隆,因此我编写了这段代码。除了一行之外,一切对我来说都很清楚。它是第 5 行的析构函数 Destructor myClass1 0x28fec0
。它来自哪里,为什么叫它?
控制台输出:
Constructor myClass1 0x28fe98
Constructor myClass2 0x28fe88
Constructor myClass3 0x28fe78
operator=
Destructor myClass1 0x28fec0
clone
Constructor clone 0x28fed0
operator=
Destructor clone 0x28fed0
Destructor myClass3 0x28fe78
Destructor myClass2 0x28fe88
Destructor myClass1 0x28fe98
主要.cpp:
#include <iostream>
#include "MyClass.h"
int main(){
MyClass myClass1("myClass1"), myClass2("myClass2"), myClass3("myClass3");
myClass2 = myClass1;
myClass3 = myClass1.clone();
return 0;
}
我的类.h:
#ifndef MYCLASS_H
#define MYCLASS_H
#include <iostream>
#include <string>
class MyClass{
private:
int *values;
int size;
int *copies;
std::string name;
public:
MyClass();
MyClass(std::string name);
~MyClass();
void operator=(MyClass myClass);
MyClass clone();
};
#endif
我的类.cpp:
#include "MyClass.h"
MyClass::MyClass(){
std::cout << "Constructor" << this << std::endl;
name = "None";
size = 1;
values = new int[1];
values[0] = 0;
copies = new int;
*copies = 1;
count++;
}
MyClass::MyClass(std::string name){
std::cout << "Constructor " << name << " " << this << std::endl;
size = 1;
values = new int[1];
values[0] = 0;
copies = new int;
*copies = 1;
count++;
this->name = name;
}
MyClass::~MyClass(){
std::cout << "Destructor " << name << " " << this << std::endl;
if(*copies == 1){
delete [] values;
values = 0;
delete copies;
copies = 0;
}
count--;
}
void MyClass::operator=(MyClass myClass){
std::cout << "operator=" << std::endl;
if(*copies == 1){
delete copies;
copies = 0;
delete [] values;
values = 0;
}
size = myClass.size;
values = myClass.values;
copies = myClass.copies;
(*copies)++;
}
MyClass MyClass::clone(){
std::cout << "clone" << std::endl;
MyClass myClass("clone");
myClass.size = size;
delete [] myClass.values;
myClass.values = new int[size];
for(int i = 0; i < size; i++){
myClass.values[i] = values[i];
}
return myClass;
}
最佳答案
因为您将 operator=
的参数作为拷贝。
因此它在 operator=
中创建了一个 MyClass
对象,当 operator=
返回时该对象被销毁。
关于C++为什么调用这个析构函数,它从哪里来,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/29187521/