C++时间标准库时间time和系统时间的使用

1. C++标准库中的时间需要引用time.h，可以取的本地时间或者格林威治时间，只能精确到秒

#include <iostream>

/*包含time头文件*/
#include <time.h>


using namespace std;

int main()
{
	//time_t是long类型，精确到秒，是当前时间和1970年1月1日零点时间的差
	const time_t t = time(NULL);

	cout<<"current time is "<<t<<endl;

	/*本地时间：日期，时间 年月日，星期，时分秒*/
	struct tm* current_time = localtime(&t);
	printf("current year is %d;current month is %d;current date of month is %d\r\n",
		1900 + current_time->tm_year,
		1 + current_time->tm_mon/*此month的范围为0-11*/,
		current_time->tm_mday);

	printf("current day of year is %d;current day in week is %d\r\n",
		current_time->tm_yday,/*当前日期是今年的第多少天[0,365] */
		current_time->tm_wday/*days since Sunday - [0,6] */);

	printf("time part %d:%d:%d \r\n",
		current_time->tm_hour,
		current_time->tm_min,
		current_time->tm_sec);

	printf("\t本地时间：%d-%d-%d %d:%d:%d\r\n",
		current_time->tm_year + 1900,
		current_time->tm_mon + 1,
		current_time->tm_mday,
		current_time->tm_hour,
		current_time->tm_min,
		current_time->tm_sec);

	/*格林威治时间*/
	struct tm* current_gmtime = gmtime(&t);

	printf("格林威治时间：%d-%d-%d %d:%d:%d\r\n",
		current_gmtime->tm_year + 1900,
		current_gmtime->tm_mon + 1,
		current_gmtime->tm_mday,
		current_gmtime->tm_hour,
		current_gmtime->tm_min,
		current_gmtime->tm_sec);


	system("pause");
	return 0;
}

2. 系统时间 SYSTEMTIME 使用时要引用windows.h，可以精确到毫秒级别

#include <iostream>
#include <Windows.h>


int main(){
	//声明变量
	SYSTEMTIME sys_time;

	//将变量值设置为本地时间
	GetLocalTime( &sys_time );

	//输出时间
	printf( "%4d/%02d/%02d %02d:%02d:%02d.%03d 星期%1d\n",sys_time.wYear,
		sys_time.wMonth,
		sys_time.wDay,
		sys_time.wHour,
		sys_time.wMinute, 
		sys_time.wSecond,
		sys_time.wMilliseconds,
		sys_time.wDayOfWeek);

	system("time");

	system("pause");
	return 0;
}