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C time.h library functions:
All C inbuilt functions which are declared in time.h header file are given below. The source code for time.h header file is also given below for your reference.
List of inbuilt C functions in time.h file:
Below are the list of time related fuctions in C programming language. Please refer C – time related functions page for sample program and output for each below functions.
| Functions | Description |
| setdate() | This function used to modify the system date |
| getdate() | This function is used to get the CPU time |
| clock() | This function is used to get current system time |
| time() | This function is used to get current system time as structure |
| difftime() | This function is used to get the difference between two given times |
| strftime() | This function is used to modify the actual time format |
| mktime() | This function interprets tm structure as calendar time |
| localtime() | This function shares the tm structure that contains date and time informations |
| gmtime() | This function shares the tm structure that contains date and time informations |
| ctime() | This function is used to return string that contains date and time informations |
| asctime() | Tm structure contents are interpreted by this function as calendar time. This time is converted into string. |
Source code for time.h header file:
Please find the source code for time.h header file below. This code is taken from DevC++ compiler files for your reference.
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/* * time.h * This file has no copyright assigned and is placed in the Public Domain. * This file is a part of the mingw-runtime package. * No warranty is given; refer to the file DISCLAIMER within the package. * * Date and time functions and types. * */ #ifndef _TIME_H_ #define _TIME_H_ /* All the headers include this file. */ #include <_mingw.h> #define __need_wchar_t #define __need_size_t #define __need_NULL #ifndef RC_INVOKED #include <stddef.h> #endif /* Not RC_INVOKED */ /* * Number of clock ticks per second. A clock tick is the unit by which * processor time is measured and is returned by 'clock'. */ #define CLOCKS_PER_SEC ((clock_t)1000) #define CLK_TCK CLOCKS_PER_SEC #ifndef RC_INVOKED /* * A type for storing the current time and date. This is the number of * seconds since midnight Jan 1, 1970. * NOTE: This is also defined in non-ISO sys/types.h. */ #ifndef _TIME_T_DEFINED typedef long time_t; #define _TIME_T_DEFINED #endif #ifndef __STRICT_ANSI__ /* A 64-bit time_t to get to Y3K */ #ifndef _TIME64_T_DEFINED typedef __int64 __time64_t; #define _TIME64_T_DEFINED #endif #endif /* * A type for measuring processor time (in clock ticks). */ #ifndef _CLOCK_T_DEFINED typedef long clock_t; #define _CLOCK_T_DEFINED #endif #ifndef _TM_DEFINED /* * A structure for storing all kinds of useful information about the * current (or another) time. */ struct tm { int tm_sec; /* Seconds: 0-59 (K&R says 0-61?) */ int tm_min; /* Minutes: 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 Jan. 1: 0-365 */ int tm_isdst; /* +1 Daylight Savings Time, 0 No DST, * -1 don't know */ }; #define _TM_DEFINED #endif #ifdef __cplusplus extern "C" { #endif _CRTIMP clock_t __cdecl clock (void); _CRTIMP time_t __cdecl time (time_t*); _CRTIMP double __cdecl difftime (time_t, time_t); _CRTIMP time_t __cdecl mktime (struct tm*); /* * These functions write to and return pointers to static buffers that may * be overwritten by other function calls. Yikes! * * NOTE: localtime, and perhaps the others of the four functions grouped * below may return NULL if their argument is not 'acceptable'. Also note * that calling asctime with a NULL pointer will produce an Invalid Page * Fault and crap out your program. Guess how I know. Hint: stat called on * a directory gives 'invalid' times in st_atime etc... */ _CRTIMP char* __cdecl asctime (const struct tm*); _CRTIMP char* __cdecl ctime (const time_t*); _CRTIMP struct tm* __cdecl gmtime (const time_t*); _CRTIMP struct tm* __cdecl localtime (const time_t*); _CRTIMP size_t __cdecl strftime (char*, size_t, const char*, const struct tm*); #ifndef __STRICT_ANSI__ extern _CRTIMP void __cdecl _tzset (void); #ifndef _NO_OLDNAMES extern _CRTIMP void __cdecl tzset (void); #endif _CRTIMP char* __cdecl _strdate(char*); _CRTIMP char* __cdecl _strtime(char*); /* These require newer versions of msvcrt.dll (6.10 or higher). */ #if __MSVCRT_VERSION__ >= 0x0601 _CRTIMP __time64_t __cdecl _time64( __time64_t); _CRTIMP __time64_t __cdecl _mktime64 (struct tm*); _CRTIMP char* __cdecl _ctime64 (const __time64_t*); _CRTIMP struct tm* __cdecl _gmtime64 (const __time64_t*); _CRTIMP struct tm* __cdecl _localtime64 (const __time64_t*); #endif /* __MSVCRT_VERSION__ >= 0x0601 */ /* * _daylight: non zero if daylight savings time is used. * _timezone: difference in seconds between GMT and local time. * _tzname: standard/daylight savings time zone names (an array with two * elements). */ #ifdef __MSVCRT__ /* These are for compatibility with pre-VC 5.0 suppied MSVCRT. */ extern _CRTIMP int* __cdecl __p__daylight (void); extern _CRTIMP long* __cdecl __p__timezone (void); extern _CRTIMP char** __cdecl __p__tzname (void); __MINGW_IMPORT int _daylight; __MINGW_IMPORT long _timezone; __MINGW_IMPORT char *_tzname[2]; #else /* not __MSVCRT (ie. crtdll) */ #ifndef __DECLSPEC_SUPPORTED extern int* _imp___daylight_dll; extern long* _imp___timezone_dll; extern char** _imp___tzname; #define _daylight (*_imp___daylight_dll) #define _timezone (*_imp___timezone_dll) #define _tzname (*_imp___tzname) #else /* __DECLSPEC_SUPPORTED */ __MINGW_IMPORT int _daylight_dll; __MINGW_IMPORT long _timezone_dll; __MINGW_IMPORT char* _tzname[2]; #define _daylight _daylight_dll #define _timezone _timezone_dll #endif /* __DECLSPEC_SUPPORTED */ #endif /* not __MSVCRT__ */ #ifndef _NO_OLDNAMES #ifdef __MSVCRT__ /* These go in the oldnames import library for MSVCRT. */ __MINGW_IMPORT int daylight; __MINGW_IMPORT long timezone; __MINGW_IMPORT char *tzname[2]; #else /* not __MSVCRT__ */ /* CRTDLL is royally messed up when it comes to these macros. TODO: import and alias these via oldnames import library instead of macros. */ #define daylight _daylight /* NOTE: timezone not defined because it would conflict with sys/timeb.h. Also, tzname used to a be macro, but now it's in moldname. */ __MINGW_IMPORT char *tzname[2]; #endif /* not __MSVCRT__ */ #endif /* Not _NO_OLDNAMES */ #endif /* Not __STRICT_ANSI__ */ #ifndef _WTIME_DEFINED /* wide function prototypes, also declared in wchar.h */ #ifndef __STRICT_ANSI__ #ifdef __MSVCRT__ _CRTIMP wchar_t* __cdecl _wasctime(const struct tm*); _CRTIMP wchar_t* __cdecl _wctime(const time_t*); _CRTIMP wchar_t* __cdecl _wstrdate(wchar_t*); _CRTIMP wchar_t* __cdecl _wstrtime(wchar_t*); #if __MSVCRT_VERSION__ >= 0x0601 _CRTIMP wchar_t* __cdecl _wctime64 (const __time64_t*); #endif #endif /* __MSVCRT__ */ #endif /* __STRICT_ANSI__ */ _CRTIMP size_t __cdecl wcsftime (wchar_t*, size_t, const wchar_t*, const struct tm*); #define _WTIME_DEFINED #endif /* _WTIME_DEFINED */ #ifdef __cplusplus } #endif #endif /* Not RC_INVOKED */ #endif /* Not _TIME_H_ */ |