我通常不建议使用singleton类是好的风格，我会做什么：

I would not generally advise to use singleton classes is good style, but here's what I would do:

MySingleton.hpp：

class MySingleton {
public:
    static MySingleton& instance() {
        static MySingleton theInstance;
        return theInstance;
    }
    std::vector<int>& levels() { return levels_; }

private:
    MySingleton() {
    }
    std::vector<int> levels_;
};

要在其他地方使用上述内容：

To use the above elsewhere:

#include "MySingleton.hpp"

// ...
MySingleton::instance().levels().resize(10); // Creates 10 ints initialized to 0

为了缩短访问时间，自己的命名空间并提供免费的函数：

To shorten the access you could even wrap the whole thing in its own namespace and provide free functions there:

namespace MySpace {
    class MySingleton {
        // Blah, blah
    };

    std::vector& levels() {
        return MySingleton::instance().levels();
    }
}

并使用

MySpace::levels().resize(10);