C++构造函数、继承、访问修饰符等等
// Inheritance.cpp : main project file.
#include "stdafx.h"
using namespace System;
ref class Base {
private:
int value;
int value2;
Base() { this->value2 = 4; }
protected:
Base(int n) {
Base(); // <- here is my problem
value = n;
}
int get(){ return value; }
int get2(){ return value2; }
};
ref class Derived : Base {
public:
Derived(int n) : Base(n) { }
void println(){
Console::WriteLine(Convert::ToInt32(get()));
Console::WriteLine(Convert::ToInt32(get2()));
}
};
int main(array<System::String ^> ^args) {
Derived ^obj = gcnew Derived(5);
obj->println();
Console::ReadLine();
}
控制台输出是：
0
5
我知道，我确实调用了 Base() 构造函数，并且我知道我创建了一个类似新对象的东西，该对象在调用 Base(int n) 后消失了......
但我不知道如何才能将我的私有默认构造函数与受保护的构造函数结合起来。
（我通过 Visual-studio-2010 使用 .NET 框架，但我认为这更像是一个一般的 C++ 问题）
// Inheritance.cpp : main project file.
#include "stdafx.h"
using namespace System;
ref class Base {
private:
int value;
int value2;
Base() { this->value2 = 4; }
protected:
Base(int n) {
Base(); // <- here is my problem
value = n;
}
int get(){ return value; }
int get2(){ return value2; }
};
ref class Derived : Base {
public:
Derived(int n) : Base(n) { }
void println(){
Console::WriteLine(Convert::ToInt32(get()));
Console::WriteLine(Convert::ToInt32(get2()));
}
};
int main(array<System::String ^> ^args) {
Derived ^obj = gcnew Derived(5);
obj->println();
Console::ReadLine();
}
Console Output is:
0
5
i know, that i do call the Base() constructor, and i know that i create something like a new object, that vanishes after Base(int n) was called...
but i have no idea how i could combine my private default constructor with the protected one.
(i am using the .NET framework via visual-studio-2010, but i think this is more like a general c++ problem)
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评论（3）
当我遇到这种情况时，我添加了一个成员函数来初始化公共值，例如在两个构造函数上调用的 Init 方法。
When I face this situation I added a member function for initializing common values, like for example an Init method called on both constructors.
使用方法
例如，将此方法命名为
init()。use method
name this method
init(), for example.Base()构造函数使value未初始化，我什至不确定是否需要该构造函数，因为它是private。只需确保您充分定义了公共 API 并且仅创建所需的构造函数。然后在每个构造函数中使用初始化列表来分配所有属性，以避免使用未初始化的内存（通常尝试避免在主体或单独的方法中分配，以避免可能的双重初始化。
The
Base()constructor leavesvalueuninitialized and I'm not even sure that constructor is needed at all since it'sprivate.Just make sure that you adequately define your public API and only create constructors that are needed. Then in each constructor use the initializer list to assign all the attributes, to avoid working with uninitalized memory (typically try to avoid assigning in the body or a separate method to avoid possible double initialization.