TIME.h — Wikipedia

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A wikipedia article, free l’encyclopéi.

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And are headers, respectively of the standard library of the C and C ++ language, which declare functions providing standardized manipulation of dates and their formatting.

char * asctime (const struct tm* tmptr )

Converted tmptr in a character string in format Www Mmm dd hh:mm:ss yyyy , Or Www is the day of the week, Mmm is the month in letters, dd The day of the month, hh:mm:ss is time, and yyyy is the year. The chain is followed by a return to the line and an end of the chain, for a total of 26 characters. The result chain is allocated statically and shared by the functions ctime And asctime . Each time one of the two functions is called, the content this chain is replaced.

clock_t clock (void)

Returns an approximation of the processor time used by the process.

char* ctime (const time_t* timer )

Converts the value timer in a chain in the same format as asctime . The returned chain is allocated statically in a shared area with asctime . ctime uses the internal buffer of gmtime And localtime As a return pointer, a call to this function will therefore cause crushing.

double difftime (time_t Timer2 , time_t Timer1 )

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Returns the difference, expressed in seconds between two moments.

struct tm* gmtime (const time_t* timer )

Converts a type value time_t In a TM structure in UTC time. This structure is allocated statically and shared by the functions gmtime , localtime And ctime . Each time one of these functions is called, the content of the structure is crushed.

struct tm* gmtime_r (const time_t* timer , struct tm* result )

Converts a type value time_t In a TM structure in UTC time. The date is stored in the TM structure pointed out by result . This is a version compatible with the threads of gmtime .

struct tm* localtime (const time_t* timer )

Converts a type value time_t in a TM structure at local time. This structure is allocated statically and shared by the functions gmtime , localtime And ctime . Each time one of these functions is called, the content of the structure is crushed.

time_t mktime (struct tm* ptm )

Converts a structure tm in a type of type time_t . mktime Check the TM structure, by correcting the values ​​of its attributes if they are poorly informed, and translates this structure into a value time_t which has returned. The original values ​​of the fields tm_wday And tm_yday (day of week and year) of ptm are ignored, but the fields are filled with the values ​​that correspond to the calculated date. The value of tm_day is not checked until tm_wday And tm_yday are determined. In the event of an error, the function returns the value (time_t)-1 .

time_t time (time_t* timer )

Gives current time. The value is stored in the object pointed out by timer . In the case where timer is zero, the value has only passed as a result of the function. Standard C specifies that the type time_t is arithmetic, but that its encoding is not specified, which makes this type practically opaque. The POSIX standard specifies that time_t contains the number of seconds since (Unix time).

size_t strftime (char* s , size_t n , const char* format , const struct tm* tptr )

Formed at the structure tm in a character string, written in s , which contains at most n characters.
CLK_PER_SEC
Constant that defines the number of clock blows per second. It is used by the function clock() .
CLOCKS_PER_SEC
Another name of CLK_PER_SEC used by a few libraries.
CLK_TCK
An obsolete macro from CLK_PER_SEC.
clock_t
Type of data returned by Clock ().
Generally defined by types int or long int .
time_t
Type of data returned by Time ().
Generally defined by types int or long int .
struct tm
Human representation and calendar of dates.

Calendar [ modifier | Modifier and code ]

The human representation of dates (“Broken-Down Time” in English) is represented in the standard library C by the structure struct tm Here are the members:

Member Description
int tm_hour Time (0 – 23)
int tm_isdst Indicator on the offset between winter and summer time: is 1 if the discrepancy is active, 0 if it is not and a negative value if the information is not available.
int tm_mday Day of the month (1 – 31)
int tm_min minutes (0 – 59)
int tm_mon months (0 – 11, 0 corresponds to January)
int tm_sec seconds (0 – 59)
int tm_wday Day of the week (0-6, 0 corresponds to Sunday)
int tm_yday Day of year (0 – 365)
int tm_year number of years since 1900
  • (in) The GNU C Library ReferenceManual , ( read online ) , « Calendar Time »
  • (in) The Open Group BaseSpecifications , ( read online ) , «Gmtime»

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