C + + Time acquisition

Http://net.pku.edu.cn/~yhf/linux_c/function/04.html

	Asctime (the time and date are represented in string format)
Related functions	Time,ctime,gmtime,localtime
Table header File	#include <time.h>
Defining functions	char * asctime (const struct TM * timeptr);
Function description	Asctime () Converts the information in the TM structure referred to by the parameter timeptr to the time-date representation used by the real world, and then returns the result in string form. This function has been converted from time zone to local time, and the string format is: "Wed June 21:49:08 1993\n"
return value	If the associated time-date function is called again, the string may be corrupted. This function differs from CTime in that the parameters passed in are different structures.
Additional Instructions	Returns a string representing the current local time date.
Example	#include <time.h> Main () { time_t TIMEP; Time (&TIMEP); printf ("%s", Asctime (Gmtime (&TIMEP))); }
Perform	Sat Oct 28 02:10:06 2000
	CTime (the time and date are represented in string format)
Related functions	Time,asctime,gmtime,localtime
Table header File	#include <time.h>
Defining functions	Char *ctime (const time_t *TIMEP);
Function description	CTime () Converts the information in the time_t structure referred to by the parameter TIMEP to the time-date representation used by the real world, and then returns the result in string form. This function has been converted from time zone to local time, and the string format is "Wed June 21:49:08 1993\n". If the associated time-date function is called again, the string may be corrupted.
return value	Returns a string representing the current local time date.
Example	#include <time.h> Main () { time_t TIMEP; Time (&TIMEP); printf ("%s", CTime (&TIMEP)); }
Perform	Sat Oct 28 10:12:05 2000
	Gettimeofday (get current time)
Related functions	Time,ctime,ftime,settimeofday
Table header File	#include <sys/time.h> #include <unistd.h>
Defining functions	int gettimeofday (struct timeval * TV, struct timezone * tz)
Function description	Gettimeofday () returns the current time with a structure referred to by TV, and the local time zone information is placed in the structure that TZ refers to. The TIMEVAL structure is defined as: struct timeval{ Long tv_sec; /* sec */ Long tv_usec; /* microseconds */ }; The timezone structure is defined as: struct timezone{ int tz_minuteswest; /* and Greenwich TIME DIFFERENCE how many minutes */ int tz_dsttime; /* Daylight Saving Time status */ }; Both of these structures are defined in/usr/include/sys/time.h. The status represented by Tz_dsttime is as follows Dst_none/* Do not use */ DST_USA/* USA */ Dst_aust/* Australia */ Dst_wet/* Western Europe * Dst_met/* Central Europe * Dst_eet/* Eastern Europe * Dst_can/* Canada */ DST_GB/* Britannia */ Dst_rum/* Romania */ Dst_tur/* Turkey * * Dst_austalt/* Australia (after 1986) */
return value	The success returns 0, the failure returns 1, and the error code is stored in errno. Additional instructions efault the memory space referred to by the pointer TV and TZ exceeds the access permission.
Example	#include <sys/time.h> #include <unistd.h> Main () { struct Timeval TV; struct timezone tz; Gettimeofday (&TV, &tz); printf ("TV_SEC; %d\n ", tv,.tv_sec); printf ("TV_USEC; %d\n ", tv.tv_usec); printf ("Tz_minuteswest; %d\n ", tz.tz_minuteswest); printf ("Tz_dsttime,%d\n", tz.tz_dsttime); }
Perform	tv_sec:974857339 tv_usec:136996 tz_minuteswest:-540 tz_dsttime:0
	Gmtime (get current time and date)
Related functions	Time,asctime,ctime,localtime
Table header File	#include <time.h>
Defining functions	struct Tm*gmtime (const TIME_T*TIMEP);
Function description	Gmtime () Converts the information in the time_t structure referred to by the parameter TIMEP to the time-date representation used by the real world, and then returns the result from the Fabric TM. The structure TM is defined as struct TM { int tm_sec; int tm_min; int tm_hour; int tm_mday; int Tm_mon; int tm_year; int tm_wday; int tm_yday; int tm_isdst; }; The int tm_sec represents the current number of seconds, the normal range is 0-59, but is allowed to 61 seconds int Tm_min represents current score, range 0-59 int Tm_hour The number of hours from midnight, with a range of 0-23 int Tm_mday The number of days in the current month, range 01-31 The int Tm_mon represents the current month, starting from January, ranging from 0-11 int tm_year number of years since 1900 int Tm_wday The number of days of the week, starting from Monday, with a range of 0-6 int Tm_yday The number of days since January 1 this year, ranging from 0-365 int TM_ISDST Daylight Saving time flag The time date returned by this function is not converted by the time zone, but UTC time.
return value	Returns the structure TM representing the current UTC time
Example	#include <time.h> Main () { Char *wday[]={"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"}; time_t TIMEP; struct TM *p; Time (&TIMEP); P=gmtime (&TIMEP); printf ("%d%d%d", (1900+p->tm_year), (1+p->tm_mon), p->tm_mday); printf ("%s%d;%d;%d\n", Wday[p->tm_wday], P->tm_hour, P->tm_min, p->tm_sec); }
Perform	2000/10/28 Sat 8:15:38
	LocalTime (get local current time and date)
Related functions	Time, Asctime, CTime, gmtime
Table header File	#include <time.h>
Defining functions	struct TM *localtime (const time_t * TIMEP);
Function description	LocalTime () Converts the information in the time_t structure referred to by the parameter TIMEP to the time-date representation used by the real world, and then returns the result from the Fabric TM. Please refer to Gmtime () for the definition of structure TM. The time date returned by this function has been converted to the local time zone.
return value	Returns the structure TM representing the current local time.
Example	#include <time.h> Main () { Char *wday[]={"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"}; time_t TIMEP; struct TM *p; Time (&TIMEP); P=localtime (&TIMEP); /* Get local time */ printf ("%d%d%d", (1900+p->tm_year), (L+p->tm_mon), p->tm_mday); printf ("%s%d:%d:%d\n", Wday[p->tm_wday],p->tm_hour, P->tm_min, p->tm_sec); }
Perform	2000/10/28 Sat 11:12:22
	Mktime (Converts the time structure data to elapsed seconds)
Related functions	Time,asctime,gmtime,localtime
Table header File	#include <time.h>
Defining functions	time_t mktime (Strcut TM * timeptr);
Function description	The Mktime () is used to convert the TM structure data referred to by the parameter timeptr to the number of seconds elapsed since the UTC time of January 1, 1970 0:0 0 seconds.
return value	Returns the number of seconds elapsed.
Example	/* Take time (in seconds) using localtime () Convert to a struct TM and then use Mktine () to convert the struct TM to the original number of seconds */ #include <time.h> Main () { time_t TIMEP; Strcut TM *p; Time (&TIMEP); printf ("Time ():%d \ n", TIMEP); P=localtime (&TIMEP); TIMEP = Mktime (p); printf ("Time ()->localtime ()->mktime ():%d\n", TIMEP); }
Perform	Time (): 974943297 Time ()->localtime ()->mktime (): 974943297
	Settimeofday (set current time)
Related functions	Time,ctime,ftime,gettimeofday
Table header File	#include <sys/time.h> #include <unistd.h>
Defining functions	int settimeofday (const struct timeval *tv,const struct timezone *tz);
Function description	Settimeofday () Sets the current time to the structure information referred to by TV, and the local time zone information is set to the structure referred to by TZ. Please refer to Gettimeofday () for detailed instructions. Note that only root permissions can be used to modify the time of this function.
return value	The success returns 0, the failure returns 1, and the error code is stored in errno.
Error code	Eperm does not call Settimeofday () by root, and does not have sufficient permissions. EINVAL time zone or some data is incorrect and cannot be set correctly.
	Time (get current)
Related functions	Ctime,ftime,gettimeofday
Table header File	#include <time.h>
Defining functions	time_t time (time_t *t);
Function description	This function returns the number of seconds from 0:0 to 0 seconds since the UTC time in A.D. January 1, 1970. If T is not a null pointer, this function also saves the return value to the memory referred to by the T-pointer.
return value	Success returns the number of seconds, and failure returns the ((time_t)-1) value, which causes the error to exist in errno.
Example	#include <time.h> Mian () { int seconds= time ((time_t*) NULL); printf ("%d\n", seconds); }
Perform	9.73E+08

C + + Time acquisition