Conversion of time and string

1, the common time storage method
1) The time_t type, which is essentially a long integer, represents the number of seconds from 1970-01-01 00:00:00 to the current time elapsed, and if more precise is needed, the timeval can be used precisely to milliseconds.
2) The TM structure, which is essentially a struct, 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_hour;    /* 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 represents the number of years from 1900 to the current time interval, if the value is set manually, TM_ISDST usually takes a value of-1.

2, the time function commonly used

time_t time (time_t *t); Obtained from January 1, 1970 to present the number of seconds char *asctime (const struct TM *TM); Converts the information in the structure to the real-world time, displaying the char *ctime (const time_t *TIMEP) as a string; Convert TIMEP to Real world time, with string display, it differs from asctime in that the Parameter form passed in is not the same as the struct TM *gmtime (const time_t *TIMEP); Converting the time represented by time_t to UTC time without time zone conversion is a struct TM struct pointer struct TM *localtime (const time_t *TIMEP); Similar to Gmtime, but it is time-zone-converted. time_t mktime (struct TM *tm); Converts the time of the struct TM structure to the number of seconds from 1970 to date int gettimeofday (struct timeval *tv, struct timezone *tz); Returns the number of seconds and subtleties of the current distance of 1970, followed by the TZ is the time zone, generally not double difftime (time_t time1, time_t time2); Returns the number of seconds between two time differences

3. Conversion of time and string

The header files that need to be included are

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

1) Unix/windows time-to-string reference code

time_t T;  Seconds Time tm* local; local time tm* GMT;   GMT Char buf[128]= {0};t = time (NULL); Get current seconds time local = LocalTime (&t); Convert to local time strftime (buf, +, "%y-%m-%d%h:%m:%s", local), Std::cout << buf << std::endl;gmt = gmtime (&t);// Converted to GMT Strftime (buf,%y-%m-%d%h:%m:%s, GMT), Std::cout << buf << Std::endl;

2) Unix string turn Time reference code

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_); Convert String to tm time TM_.TM_ISDST = -1;t_  = mktime (&tm_);//Convert TM time to seconds t_ + = 3600;  Number of seconds plus 3600tm_ = *localtime (&t_);//Output Time strftime (buf, +, "%y-%m-%d%h:%m:%s", &tm_); Std::cout << BUF < < 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", &year, &month, &day, &hour, &minute, &second);    Tm_.tm_year  = year-1900;    Tm_.tm_mon   = month-1;    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_); Has lost 8 time zones    return t_;//Second time}

Conversion of time and string