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class ExecuteOnExit{
public:
    ExecuteOnExit() = default;

    // movable
    ExecuteOnExit(ExecuteOnExit&& ) = default;
    ExecuteOnExit& operator=(ExecuteOnExit&& ) = default;

    // non copyable
    ExecuteOnExit(const ExecuteOnExit& e) = delete;
    void operator=(const ExecuteOnExit& f) = delete;

    template <typename F, typename... Args>
    ExecuteOnExit(F&& f, Args&&... args) {
        func_ = std::bind(std::forward<F>(f), std::forward<Args>(args)...);
    }

    ~ExecuteOnExit() noexcept {
        if (func_) func_();
    }
private:
    std::function<void ()> func_;
};

#define _CONCAT(a,b) a##b
#define _MAKE_DEFER(line) ExecuteOnExit _CONCAT(defer,line) = [&]()
#define DEFER _MAKE_DEFER(__LINE__)

static double get_cur_time(){
    struct timeval tv;
    gettimeofday(&tv, NULL);
    double ts = tv.tv_sec + tv.tv_usec/(1000.0*1000.0);
    return ts*1000;
}

class ElapseTime{
public:
    ElapseTime() = default;

    // movable
    ElapseTime(ElapseTime&& ) = default;
    ElapseTime& operator=(ElapseTime&& ) = default;

    // non copyable
    ElapseTime(const ElapseTime& e) = delete;
    void operator=(const ElapseTime& f) = delete;

    double operator()() const{
        return elpased_time_;
    };

    template <typename F, typename... Args>
    ElapseTime(F&& f, Args&&... args) {
        std::function<void ()> func_ = std::bind(std::forward<F>(f), std::forward<Args>(args)...);
        double start = get_cur_time();
        func_();
        double end = get_cur_time();
        elpased_time_ = end - start;
    }
    
    double get_elpased_time(){
        return elpased_time_;
    }

    ~ElapseTime() {
    }
    private:
        double elpased_time_;
};
static std::ostream& operator<<(std::ostream &os,const ElapseTime& et){
    os<<et();
    return os;
};


#define ELAPED_TIME(name) ElapseTime name = [&]()

//1.
//#include <iostream>
//#include <sstream>
	
    double a=35.000,b=14.967;	
    std::ostringstream   ostr; 
	ostr   <<   "a+b="   <<   a   <<   "+"   <<   b   <<   "="   <<   a+b;
	std::string str = ostr.str();

//2.
char buf[1024];
sprintf(buf,"a+b=%f+%f=%f",a,b,a+b);
memset(buf,0,sizeof(buf));			

    //#include <fstream> 
    //#include <streambuf> 
    //#include <string> 
    ifstream ifs(config_file);
    if (ifs.is_open()){
        DEFER{ifs.close();};
        string buf((istreambuf_iterator<char>(ifs)),istreambuf_iterator<char>());
    }

	inline
std::vector<std::string> split(const std::string& str, char seperator) {
    std::vector<std::string> results;

    std::string::size_type start = 0;
    std::string::size_type sep = str.find(seperator);
    while (sep != std::string::npos) {
        if (start < sep)
            results.emplace_back(str.substr(start, sep - start));

        start = sep + 1;
        sep = str.find(seperator, start);
    }

    if (start != str.size())
        results.emplace_back(str.substr(start));

    return results;
}

//#include <time.h>
//#include <chrono>  
//毫秒级
std::time_t getTimeStamp()
{
    std::chrono::time_point<std::chrono::system_clock,std::chrono::milliseconds> tp = std::chrono::time_point_cast<std::chrono::milliseconds>(std::chrono::system_clock::now());//获取当前时间点
    std::time_t timestamp =  tp.time_since_epoch().count(); //计算距离1970-1-1,00:00的时间长度
    return timestamp;
}

//秒级
//#include <time.h>
time(nullptr)

inline
std::string& trim(std::string &&s) {
    if (s.empty()) 
    {
        return s;
    }
 
    s.erase(0,s.find_first_not_of(" "));
    s.erase(s.find_last_not_of(" ") + 1);
    if(s.back() == '\r' || s.back() == '\n'){
        s.erase(s.size() -1);
    }
    return s;
}