类中静态成员的作用

类中静态成员的作用就是在该类的所有对象之中共享这个变量。

如：用来对该类的对象进行计数

// the use of static member of class
#include <iostream>
class A {
private:
    static int count;
public:
    A() {
        count++;
    }

    ~A() {}

    inline int get_count() __attribute__((always_inline)) {
        return count;
    }
};

int A::count = 0;

int main() {
    A a1;
    A a2;
    A a3;
    A a4;
    A a5;
    A a6;
    A a7;
    A a8;
    std::cout << "count = " << a1.get_count() << std::endl;
}

执行：

count = 8