std::chrono::system_clock::time_point，自定义时间工具类
time_t 是32位的整数，用来存放格林威治时间1970年01月01日00时00分00秒(北京时间1970年01月01日08时00分00秒)起至现在的总秒数，不能表示毫秒，约能表示135年
_t timep(0);("%d \n", timep); //0(&timep); /*获得time_t结构的时间，UTC时间*/("%d \n", timep); //1550036706 到现在为止的秒数
//#include<time.h> tm{t tm_sec; /* 秒–取值区间为[0,59] */t tm_min; /* 分 - 取值区间为[0,59] */t tm_hour; /* 时 - 取值区间为[0,23] */t tm_mday; /* 一个月中的日期 - 取值区间为[1,31] */t tm_mon; /* 月份（从一月开始，0代表一月） - 取值区间为[0,11] */t tm_year; /* 年份，其值从1900开始 */t tm_wday; /* 星期–取值区间为[0,6]，其中0代表星期天，1代表星期一，以此类推 */};
1、需要的头文件
include
include
include <time.h>
2、std::chrono::system_clock::time_point的使用
::chrono::system_clock::time_point start_time; //默认值为 1970-01-01 08:00:00::chrono::system_clock::time_point t(std::chrono::seconds(2)) ;//初始化2秒 1970-01-01 08:00:02::cout << t.time_since_epoch().count() <<std::endl;//纳秒 2000000000::cout << std::chrono::duration_cast<std::chrono::milliseconds>(t.time_since_epoch()).count() <<std::endl;//毫秒 2000::cout << std::chrono::system_clock::now().time_since_epoch().count() <<std::endl; //纳秒 1536115134721690145_t sec= std::chrono::duration_cast<std::chrono::duration<int>> (std::chrono::system_clock::now() - t).count();//秒 1536115132::cout << sec <<std::endl;= std::chrono::duration_cast<std::chrono::seconds>//秒 1536115132 (std::chrono::system_clock::now() - t).count();::cout << sec <<std::endl;= std::chrono::duration_cast<std::chrono::milliseconds>//毫秒 1536115132721 (std::chrono::system_clock::now() - t).count();::cout << sec <<std::endl;
3、自定义的时间工具类
#ifndef TOOL_TIME_H#define TOOL_TIME_H#include<iostream>#include<chrono>#include <time.h>#include <sys/time.h>tool_time{:atic uint32_t elapse_seconds(std::chrono::system_clock::time_point &start){ return std::chrono::duration_cast<std::chrono::seconds> (std::chrono::system_clock::now() - start).count();}atic uint64_t elapse_ms(std::chrono::system_clock::time_point &start){ return std::chrono::duration_cast<std::chrono::milliseconds> (std::chrono::system_clock::now() - start).count();}atic uint32_t now_to_seconds(){ return std::chrono::duration_cast<std::chrono::seconds> (std::chrono::system_clock::now().time_since_epoch()).count();}atic uint64_t now_to_ms(){ return std::chrono::duration_cast<std::chrono::milliseconds> (std::chrono::system_clock::now().time_since_epoch()).count();}atic uint64_t now_to_us(){ return std::chrono::duration_cast<std::chrono::microseconds> (std::chrono::system_clock::now().time_since_epoch()).count();}atic uint64_t to_ms(const std::chrono::system_clock::time_point &time){ return std::chrono::duration_cast<std::chrono::milliseconds> (time.time_since_epoch()).count();}//"%Y-%m-%d %H:%M:%S"atic std::string to_str(const std::chrono::system_clock::time_point &time){ char _time[25] = {0}; time_t tt = std::chrono::system_clock::to_time_t(time); struct tm local_time; localtime_r(&tt, &local_time); strftime(_time, 22, "%Y-%m-%d %H:%M:%S", &local_time); return std::string(_time);}//"%d-%02d-%02d %02d:%02d:%02d.%03d"atic std::string to_str_ex(const std::chrono::system_clock::time_point &time){ uint64_t mill = std::chrono::duration_cast<std::chrono::milliseconds>(time.time_since_epoch()).count() -std::chrono::duration_cast<std::chrono::seconds>(time.time_since_epoch()).count()*1000; char _time[25] = {0}; time_t tt = std::chrono::system_clock::to_time_t(time); struct tm local_time; localtime_r(&tt, &local_time); //strftime(_time, 22, "%Y-%m-%d %H:%M:%S", local_time); sprintf(_time, "%d-%02d-%02d %02d:%02d:%02d.%03d", local_time.tm_year+1900, local_time.tm_mon+1, local_time.tm_mday, local_time.tm_hour, local_time.tm_min, local_time.tm_sec, mill); return std::string(_time);}atic uint64_t now_to_ms_ex(){ struct timeval tv; ::gettimeofday(&tv, 0); return tv.tv_sec*1000+tv.tv_usec/1000;}//"%Y-%m-%d %H:%M:%S"atic time_t to_time(std::string str){ time_t t_; tm tm_; strptime(str.c_str(), "%Y-%m-%d %H:%M:%S", &tm_); //将字符串转换为tm时间 t_ = mktime(&tm_); //将tm时间转换为秒时间 return t_;}"%d-%02d-%02d %02d:%02d:%02d.%03d"atic std::chrono::system_clock::time_point to_time_ex(std::string str){ int pos = str.length()-3; time_t t_; tm tm_; strptime(str.substr(0,pos).c_str(), "%Y-%m-%d %H:%M:%S", &tm_); //将字符串转换为tm时间 t_ = mktime(&tm_); //将tm时间转换为秒时间 int milli = std::stoi(str.substr(pos)); return std::chrono::system_clock::time_point(std::chrono::milliseconds(t_*1000 + milli));}atic std::string to_str_ex(uint64_t ms){ uint64_t mill = ms%1000; char _time[25] = {0}; time_t tt = ms/1000; struct tm *local_time=localtime(&tt); //strftime(_time, 22, "%Y-%m-%d %H:%M:%S", local_time); sprintf(_time, "%d-%02d-%02d %02d:%02d:%02d.%03d", local_time->tm_year+1900, local_time->tm_mon+1, local_time->tm_mday, local_time->tm_hour, local_time->tm_min, local_time->tm_sec, mill); return std::string(_time);}atic uint32_t elapse_seconds(time_t &start){ time_t now; time(&now); return static_cast<uint32_t>(std::difftime(now, start));}//"%Y-%m-%d %H:%M:%S"atic std::string to_str(const std::time_t &time){ char _time[25] = {0}; struct tm local_time; localtime_r(&time, &local_time); strftime(_time, 22, "%Y-%m-%d %H:%M:%S", &local_time); return std::string(_time);}};#endif // TOOL_TIME_H
测试
in(){to now = std::chrono::system_clock::now();d::string tt=tool_time::to_str_ex(tool_time::now_to_ms());d::string tt2=tool_time::to_str_ex(tool_time::to_ms(now));d::string tt3=tool_time::to_str(std::chrono::system_clock::to_time_t(now));d::string tt4=tool_time::to_str(now);intf("%s\n", tt.c_str());intf("%s\n", tt2.c_str());intf("%s\n", tt3.c_str());intf("%s\n", tt4.c_str());intf("%ld\n", tool_time::to_time(tt));intf("%ld\n", tool_time::now_to_seconds());intf("%ld\n", tool_time::now_to_ms()/1000);intf("%ld\n", tool_time::now_to_ms_ex()/1000);intf("%ld\n", tool_time::now_to_ms());intf("%ld\n", tool_time::now_to_ms_ex());turn 0;}
结果：
-09-23 14:03:24.941-09-23 14:03:24.941-09-23 14:03:24-09-23 14:03:24260426042604260426049412604941
转自：https://blog.csdn.net/f110300641/article/details/82147885
