查询C ++中的类的静态成员变量 [英] Query on Static member variables of a class in C++

问题描述

在C ++代码中有以下内容：

  class Foo 
 {
 public：
 static int bands; 
 ... 
 ... 
 private：
 ... 
 ... 
 
} //类定义结束
 
 int Foo :: bands; //注意：这里没有初始化任何值！ 
   
 
 
 
 
 < 
  
 
 
也可以将静态变量声明为任何类中的私有成员变量。
 
 
 
 
 
解决方案
 C ++注意到声明和。 频段在类中声明，但未定义。
 
 
 
定义该类型的对象，但由于静态成员不是任何一个特定对象的一部分，它需要它自己的定义。
 
Sorry if this question seems trivial to many here.

In a C++ code there is something as below:
class Foo
{
public:
   static int bands;
   ...
   ...
private:
   ...
   ...

}//class definition ends

int Foo::bands; //Note: here its not initialized to any value!



Why is the above statement needed again when 'bands' is once declared inside the class as static?
Also can a static variable be declared as a private member variable in any class?

解决方案
C++ notes a distinction between declaring and defining.  bands is declared within the class, but not defined.

A non-static data member would be defined when you define an object of that type, but since a static member is not a part of any one specific object, it needs it's own definition.

                        
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