如何使用另一个类的静态集初始化该集...？
class A{
static set<string> set1;
};
class B{
set<string> set2;
public:
A a;
}
in main.cpp
void B::comparision()
{
set2.insert(a.set1); //i am getting error
};
我如何使用set1的值初始化set2。
class A{
static set<string> set1;
};
class B{
set<string> set2;
public:
A a;
}
in main.cpp
void B::comparision()
{
set2.insert(a.set1); //i am getting error
};
how can i initilize set2 with the value of set1.
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评论（4）
好吧，首先您需要将
A::set1公开访问：您还可以从
B的定义中删除a，因为您不需要A的实例，您只需要访问其静态公共成员之一。然后，您的
comparison函数应按如下方式修改：请注意，
insert采用单个值并将其插入到集合中。这不足以复制整个集合。幸运的是，您有一个可以使用的赋值运算符，如上所示。Well, first you'll need
A::set1to be publicly accessible:You can also remove
afrom your definition ofB, since you don't need an instance ofA, you only need to access one of its static public members.Then your
comparisonfunction should be modified as follows:Note that
inserttakes a single value and inserts it into the set. This will not suffice to copy an entire set. Fortunately, you have an assignment operator you can use as shown above.我不确定
void B::comparison()是什么，因为您从未声明过它，但一般语法是：该语法的例外是 if
set2正在被初始化（即在类构造函数中），在这种情况下它看起来像：I'm not sure what
void B::comparison()is since you never declared it, but the general syntax would be:The exception to that syntax would be if
set2were being initialized (i.e., in a class constructor), in which case it would look like:通过初始化，我假设您想要将静态集的所有元素复制到 B 类中的集合（而不保留其以前的内容）。在这种情况下，您需要将其指定为
set2 = A::set1;By initialize I assume you want to copy all elements of the static set to the set in class B (without preserving its previous contents). In such case, you need to assign it as
set2 = A::set1;静态数据成员由类的所有对象共享，因此它不是任何对象的一部分。在这种情况下，set1 不是对象
a的一部分。所以你不能通过a.set1访问它。相反，您可以通过A::set1访问静态数据成员。正如其他人已经说过的，您需要A::set1才能公开访问。如果要将
A::set1插入到set2中，代码将如下所示：set2.insert(A::set1.begin(), A::set1.end())The static data member is shared by all objects of the class, so it is not a part of any object. In this case, set1 is not a part of object
a. So you cannot access it by a.set1. Instead you can access the static data member byA::set1. As already said by others, you needA::set1to be publicly accessible.And if you want to insert
A::set1intoset2, the code would look like:set2.insert(A::set1.begin(), A::set1.end())