C++中静态数据成员使用示例

#include<iostream>//尝试静态数据成员
using namespace std;
class easy {
private:
	int num1;
	int num2;
	static int sum,count;
	static float ave;
public:
	easy(int, int);
	easy(const easy&);//拷贝构造函数，这里要加const，否则使用时会显示没有合适的拷贝构造函数
	void output();
	~easy();
};
easy::easy(int a,int b) :num1(a), num2(b)
{
	sum += num1 + num2;
	count++;
	ave = sum / count;
}
easy::easy(const easy& m ) {
	num1 = m.num1 * 100;
	num2 = m.num2 * 100;
}
void easy::output() {
	cout << "num1=" << num1 << " " << "num2=" << num2 << endl;
	cout << "sum=" << sum << " count=" << count << " ave=" << ave << endl;
    cout << "sum         count         ave" << endl;
	cout << &sum<<"   " << &count <<"   "<< & ave<<endl;//显示地址
}
easy::~easy() {}
int easy::sum = 0;
int easy::count = 0;
float easy::ave = 0.0;
int main() 
{
	int A, B, C, D, E, F;
	cin >> A >> B >> C >> D >> E >> F;
	easy PI(A, B);
	easy complex[3]{
		easy(PI),//调用拷贝构造函数
		easy(C,D),
		easy(E,F)
	};//建立了一个有三个无名对象元素的easy类数组
	for (int i = 0; i < 3; i++) {
		complex[i].output();
	}
}

1 2 3 4 5 6

1 2 3 4 5 6
num1=100 num2=200
sum=21 count=3 ave=7
sum         count         ave
00F8C46C   00F8C470   00F8C474
num1=3 num2=4
sum=21 count=3 ave=7
sum         count         ave
00F8C46C   00F8C470   00F8C474
num1=5 num2=6
sum=21 count=3 ave=7
sum         count         ave
00F8C46C   00F8C470   00F8C474