C++朋友班
只是想确保我已经正确理解了朋友们关于这段
class A
{
friend class B;
int valueOne;
int valueTwo;
public:
int GetValueOne(){ return valueOne; }
}
class B
{
public:
A friendlyData;
int GetValueTwo(){ return friendlyData.valueTwo; }
}
main()
{
B myObject;
myObject.friendlyData.GetValueOne(); // OK?
myObject.GetValueTwo(); // OK?
}
代码的内容，如果我们忽略缺少初始化，那么 main 中的两个函数就可以了，对吗？除了做一些时髦的事情之外，他们应该没有其他方法从这些类中获取数据......在这些类的外部，BA没有可访问的数据，只有成员函数。
Just trying to make sure I have understood friends properly with this one
class A
{
friend class B;
int valueOne;
int valueTwo;
public:
int GetValueOne(){ return valueOne; }
}
class B
{
public:
A friendlyData;
int GetValueTwo(){ return friendlyData.valueTwo; }
}
main()
{
B myObject;
myObject.friendlyData.GetValueOne(); // OK?
myObject.GetValueTwo(); // OK?
}
In reference to that code about, if we ignore the lack of initialising, the two functions in main would OK right? And besides doing some funky stuff, their should be no other way to get the data from these classes... To the out side of these class, B.A has no accessible data, just the member function.
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评论（2）
是的，
main中识别的两个调用都正常。它们涉及 3 个成员的访问：B::A、B::GetValueTwo和A::GetValueOne。所有这些都具有公共可访问性并且不公开任何私有类型。因此它们可以在任何地方使用，包括main。Yes the two identified calls in
mainare OK. They involve the access of 3 members:B::A,B::GetValueTwoandA::GetValueOne. All of which havepublicaccessibility and expose no privae types. Hence they're usable from anywhere includingmain.看起来很合理，因为两个 GetValueX 方法都是公共的，因此调用没有问题。对
GetValueTwo()调用的调用利用了它的友谊。警告：友谊可能会破坏设计中的封装。
It looks reasonable as both of the
GetValueXmethods are public and so the calls are fine. The call toGetValueTwo()call makes use of its friendship.Word of warning: friendship can break the encapsulation in your design.