我的 C++ style

int g_tennis;    // not use as possible

int make_world() {
    int size = 0;

    return size;
}

const int NUMBER = 100;

enum Color {
    RED,
    GREEN
};

typedef int Dog;

class MyClass {
    public:
        MyClass(int s, int num_entries = 0)
            : size(s), num_entries_(num_entries), length_(0) {
                int book = NUMBER;
                book = 3;
            }

        int size;

        // same as data member
        int num_entries() const {
            return num_entries_;
        }

        void set_num_entries(int num_entries) {
            num_entries_ = num_entries;
        }

        // private and protected name end with underline
    private:
        int num_entries_;

        void foo_(double world) {
            double *pworld = &world;
            pworld = nullptr;
        }

    protected:
        int length_;
};

int main() {

    return 0;
}