C++结构体中的静态变量

分享一个挺有意思的代码：

#include <bits/stdc++.h>
using namespace std;

struct Point {
    static int cnt;
    Point() {
        ++cnt;
        cout << "There is " << cnt << " item(s)." << endl;
    }
    ~Point() {
        --cnt;
        cout << cnt << " item(s) remains." << endl;
    }
} ;
int Point::cnt;

int main() {
    Point a, b;
    delete (new Point());
    Point c, d;
    return 0;
}

java是可以直接在类中初始化的，不过C++的初始化要在结构体外完成，否则会在链接的时候发生找不到对象的错误。

#include <bits/stdc++.h>
using namespace std;

class TheOnlyInstance {
    public:
        static TheOnlyInstance *GetTheOnlyInstance();
        static int Parameter;
    protected:
        TheOnlyInstance() {}
} ;

//int TheOnlyInstance::Parameter = 2;

TheOnlyInstance *TheOnlyInstance::GetTheOnlyInstance() {
    static TheOnlyInstance objTheonlyInstance;
    int Parameter = 1;
    return &objTheonlyInstance;
}

int main() {
    //cout << TheOnlyInstance::Parameter << endl;
    cout << TheOnlyInstance::GetTheOnlyInstance() << endl;
    cout << TheOnlyInstance::Parameter << endl;
    return 0;
}

——Written by Lyon