server-whatever/tool_byte.h

#ifndef tool_byte_h
#define tool_byte_h
#include <vector>
#include <string>

struct tool_byte{
    
    template<class T>
    static void memcpy_int(std::vector<char>& msg, T val)
    {
        for(int i = sizeof(T) - 1; i>=0; --i)
        {
            msg.push_back((val>>(i*8))&0xff);
        }
    }

    static std::string to_cardid(const int ctype, const int cid)
    {
        char sz[20] = {0};
        sprintf(sz, "%.3d%.10d", ctype, cid);

        return std::string(sz);
    }
};

#endif