9th Lesson-Time Programming

1. GMT (UTC): World Standard Time. is based on the time standard of a place in London, England.
Calendar time: Starting at a standard point in time (1970.01.01.00:00:00:) and the number of seconds that are now experienced.
2. Function Learning
1.1 Get Calendar Time
Name of 1.1.1 function
Time
1.1.2 Function prototype
time_t time (time_t *t);
1.1.3 Function function
Return Calendar Time
1.1.4 Owning header file
<time.h>
1.1.5 return value
Success: Return from 1970.1.1.0:0:0: to current calendar time (in seconds)
Failure:-1, the corresponding error causes will be set in the global variable errno
1.1.6 parameter Description
T: Save return value if not null
1.2 Getting GMT
Name of 1.2.1 function
Gmtime
1.2.2 Function prototype
struct TM *gmtime (const time_t *TIMEP);
1.2.3 Function function
Convert calendar time to world standard Time
1.2.4 Owning header file
<time.h>
1.2.5 return value
Success: Returns the world standard Time, returned in the struct TM format.
Failure: NULL
1.2.6 parameter Description
TIMEP: The calendar time to convert.
1.3 Get local time
Name of 1.3.1 function
Loclatime
1.3.2 Function prototype
struct TM *localtime (const time_t *TIMEP);
1.3.3 function function
Converts the calendar time to local time and stores it in the TM structure.
1.3.4 Owning header file
<time.h>
1.3.5 return value
Success: Returns the local time, returned in the struct TM format.
Failure: NULL
1.3.6 parameter Description
TIMEP: Point to the calendar time you want to convert.
1.4 Displaying the time in string mode
Name of 1.4.1 function
Asctime
1.4.2 Function prototype
Char *asctime (const struct TM *TM);
1.4.3 function function
Converts the time of the struct TM format to a 26-byte string format
1.4.4 Owning header file
<time.h>
1.4.5 return value
Display time in string mode
1.4.6 parameter Description
TM: TM format time to convert
1.4.7 char* ctime (const time_t* TIMEP)
Convert calendar time directly to string time
1.5 Get high precision time
Can be used to measure the run time of a program
Name of 1.5.1 function
Gettimeofday
1.5.2 function prototype
int gettimeofday (struct timeval *tv, struct timezone *tz);
1.5.3 function function
Get high-precision time
1.5.4 Owning header file
<sys/time.h>
1.5.5 return value
Success: 0
Failed:-1
1.5.6 parameter Description
Tv: Contains the number of seconds and microseconds of the calendar time
Tz: usually null
1.5.7 UINT sleep (uint seconds);
How many seconds the program sleeps
1.5.8 void Usleep (ulong usec);
Subtle levels of hibernation

9th Lesson-Time Programming