C++静态变量

类继承的过程中静态变量共享的，无论是静态成员变量还是成员函数中的静态变量

#include <boost/filesystem.hpp>
#include <string>
#include <fstream>
#include <iostream>

class Parent {
public:
	Parent() = default;
	~Parent() = default;
	int counter() {
		static int a(0);
		return a++;
	}

	static int b;
};

int Parent::b = 0;

class Sun: public Parent {
public:
	Sun() = default;
	~Sun() = default;
};

class Daughter: public Parent {
public:
	Daughter() = default;
	~Daughter() = default;
};

int main() {
	Parent parent;
	Sun sun;
	Daughter daughter;

	std::cout << "Test of static variable in member function" << std::endl;
	std::cout << parent.counter() << std::endl;
	std::cout << sun.counter() << std::endl;
	std::cout << daughter.counter() << std::endl;

	std::cout << "Test of static member variable" << std::endl;
	std::cout << parent.b++ << std::endl;
	std::cout << sun.b++ << std::endl;
	std::cout << daughter.b++ << std::endl;

	return 0;
}

输出

Test of static variable in member function
0
1
2
Test of static member variable
0
1
2