C + + time and string conversions

1, the commonly used time storage way

1 time_t type, which is essentially a long integer representing the number of seconds from 1970-01-01 00:00:00 to the current timer, if a more precise one is needed,
You can use Timeval to be accurate to milliseconds, whose structure consists of two members, seconds, and milliseconds.

2 TM structure, which is essentially a structure, which contains the time fields

struct TM {int tm_sec/* seconds after the minute-[0,59]/int tm_min;/* minutes after the hour-[0,59]/int Tm_h Our /* Hours since midnight-[0,23] */int tm_mday; /* Day of the month-[1,31] */int tm_mon; /* months since January-[0,11] */int tm_year; /* years since 1900 */int tm_wday; /* Days since Sunday-[0,6] */int tm_yday; /* Days since January 1-[0,365] */int tm_isdst; /* Daylight Savings Time flag */};

Where tm_year indicates how many years from 1900 to the current time interval, if the value is manually set, TM_ISDST usually take a value of 1.

2, the commonly used time function

time_t time (time_t *t); Gets the number of seconds from January 1, 1970 to date char *asctime (const struct TM *TM); Converts the information in the structure to the real-world time, displaying char *ctime (const time_t *TIMEP) in string form; The time to convert TIMEP to real world, shown in strings, differs from asctime in that the parameters are passed in different forms struct TM *gmtime (const time_t *TIMEP); Converts the time represented by time_t to UTC time without time zone conversion, and is a struct TM structure pointer  struct TM *localtime (const time_t *TIMEP); But it's time to transition through time zone. time_t mktime (struct TM *tm); Converts the time of the struct TM structure to the number of seconds from 1970 to present int gettimeofday (struct timeval *tv, struct timezone); Returns the number of seconds and subtleties in the current distance of 1970, followed by the TZ of the time zone, usually without double difftime (time_t time1, time_t time2); Returns the number of seconds that differ by two times

3, time and the conversion of the string

The header files that you need to include are

#include <iostream> #include <time.h> #include <stdlib.h> #include <string.h>

1) unix/windows The reference code of the time-conversion string

void Datetimetostring () {time_t T;//sec Time tm* Local//native time  tm* GMT;//GMT char buf[128]= {0}; t = times (NULL);//Get Current seconds Time local = LocalTime (&t); Converted to local time strftime (buf,%y-%m-%d%h:%m:%s); Std::cout << buf << Std::endl; GMT = Gmtime (&t);//convert to Greenwich GMT strftime (BUF,, "%y-%m-%d%h:%m:%s", GMT); Std::cout << buf << Std::endl; }

2 Unix string turn time reference code

void Stringtodatetime () {TM tm_; time_t t_; char buf[128]= {0}; strcpy (buf, "2012-01-01 14:00:00"); Strptime (buf, "%y-%m- %d%h:%m:%s ", &tm_); Converts a string to tm time TM_.TM_ISDST =-1; T_ = Mktime (&tm_); Convert TM time to seconds t_ = 3600; Number of seconds plus 3600  tm_ = *localtime (&t_);//Output Time strftime (buf,, "%y-%m-%d%h:%m:%s", &tm_); Std::cout << BUF & lt;< Std::endl; }

3 because there is no strptime function under Windows, you can use scanf to format

time_t Stringtodatetime (char *str) {TM tm_ int year, month, day, hour, Minute,second; sscanf (str,%d-%d-%d%d:%d:%d, &tm_.) Year, &tm_.month, &tm_.day, &tm_.hour, &tm_.minute, &tm_.second); Tm_.tm_year = year-1900; Tm_.tm_mon = month; Tm_.tm_mday = day; Tm_.tm_hour = hour; Tm_.tm_min = minute; Tm_.tm_sec = second; TM_.TM_ISDST = 0; time_t t_ = mktime (&tm_); return t_; Second time}