C++的静态成员变量和静态成员函数详解

static int a = 10;//在静态区分配空间，不在堆栈

void text() {
	static int a = 10;
	a++;
	cout <<"a=" << a << endl;
}
int main(int arg, char** args) {
	text();
	text();
}

static void text() {
	int a = 10;
	a++;
	cout <<"a=" << a << endl;
}

class AA {
public:
	AA(int a, int b,int c，int d) {//错误的构造函数
		m_a = a;
		m_b = b;
		m_c = c;
		m_d = d;
	}
	static int m_c;
private:
	int m_a;
	int m_b;
	static int m_d;
};

class AA {
public:
static int m_c;
	AA(int a, int b) {
		m_a = a;
		m_b = b;
	}	
	~AA() {
		cout << "m_a=" << m_a << "	m_b=" << m_b << "	m_c=" << m_c << "	m_d=" << m_d << endl;
	}
private:
	int m_a;
	int m_b;
	static int m_d;
};
int AA::m_c = 0;//public下静态变量初始化
int AA::m_d = 1;//private下静态变量初始化
int main(int arg, char** args) {
	AA a1(1, 2);
}

class AA {
public:
	AA(int a, int b) {
		m_a = a;
		m_b = b;
	}
	static int m_c;
	int get_c() {
		m_c++;
		return m_c;
	}
private:
	int m_a;
	int m_b;
};
int AA::m_c = 0;
int main(int arg, char** args) {
	AA a1(1, 2);
	AA a2(10, 20);
	cout <<"a1(1, 2)下的c：" << a1.get_c() << endl;
	cout << "a2(10, 20)下的c：" << a2.get_c() << endl;
}

cout<<AA::m_c << endl;

class AA {
public:
	AA(int a, int b) {
		m_a = a;
		m_b = b;
	}
	static int m_c;
private:
	int m_a;
	int m_b;
};
int AA::m_c = 0;
int main(int arg, char** args) {
	AA::m_c = 100;
	cout << AA::m_c << endl; 
}

class AA {
public:
	AA(int a, int b) {
		m_a = a;
		m_b = b;
	}
	static void set_md(int d) {
		m_d = d;
	}
	static int get_md() {
		return m_d;
	}
private:
	int m_a;
	int m_b;
	static int m_d;
};
int AA::m_d = 1;
int main(int arg, char** args) {
	AA::set_md(100);
	cout << AA::get_md() << endl;	
}

class A {
private:
	int a;
	int b;
	static int c;
};
int main() {
	cout << sizeof(A) << endl;
}

#include <iOStream>
using namespace std;
class Student {
private:
	int m_id;
	double m_score;
	static int count;
	static double total_score;
public:
	Student(int id,double score) {
		m_id = id;
		m_score = score;
		count++;
		total_score += m_score;
	}
	static double get_total_score() {
		return total_score;
	}
	static double get_count() {
		return count;
	}
};
int Student::count = 0;
double Student::total_score = 0.0;
int main(int arg, char** args) {
	Student S1(1, 50.1), S2(2, 10.1), S3(3, 0.1);
	//double mean_score = 0.0;
	cout << "学生人数：" << Student::get_count() << endl;
	cout << "学生总分：" << Student::get_total_score() << endl;
	cout << "学生平均分" << Student::get_total_score() / Student::get_count() << endl;
}