C++ 时间戳和时间的互相转换

1、C++11 h毫秒级转换

#include <iostream>
#include <chrono>
#include <cstdio>

static 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());
    auto tmp = std::chrono::duration_cast<std::chrono::milliseconds>(tp.time_since_epoch());
    time_t timestamp = tmp.count();
    //std::time_t timestamp = std::chrono::system_clock::to_time_t(tp);
    return timestamp;
}

static std::tm *gettm(long long timestamp)
{
    auto milli = timestamp + (long long)8 * 60 * 60 * 1000; //此处转化为东八区北京时间，如果是其它时区需要按需求修改
    auto mTime = std::chrono::milliseconds(milli);
    auto tp = std::chrono::time_point<std::chrono::system_clock, std::chrono::milliseconds>(mTime);
    auto tt = std::chrono::system_clock::to_time_t(tp);
    std::tm *now = gmtime(&tt);
    //printf("%4d年%02d月%02d日 %02d:%02d:%02d
", now->tm_year + 1900, now->tm_mon + 1, now->tm_mday, now->tm_hour, now->tm_min, now->tm_sec);
    return now;
}

2、秒级别的

#include "iostream"
#include "time.h"
#include "string.h"
 
using namespace std;
 
int main()
{
    time_t now;                                                                                                                      
    int unixTime = (int)time(&now);
    time_t tick = (time_t)unixTime;  
 
    struct tm tm;   
    char s[100];  
    tm = *localtime(&tick);  
 
    strftime(s, sizeof(s), "%Y-%m-%d %H:%M:%S", &tm);  
    printf("%d: %s
", (int)unixTime, s);   
 
    return 0;
}