time.h.man (2225B)
1 .TH time.h 3 scc\-VERSION 2 .SH NAME 3 time.h - time and date types and functions 4 .SH SYNOPSIS 5 6 #include <time.h> 7 8 The time.h header declares the following functions: 9 10 .nf 11 char asctime(const struct tm *tm); 12 clock_t clock(void); 13 char ctime(const time_t *timep); 14 double difftime(time_t t1, time_t t2); 15 struct tm *gmtime(const time_t *timep); 16 struct tm *localtime(const time_t *timep); 17 time_t mktime(struct tm *tm); 18 size_t strftime(char *restrict, size_t, const char *restrict, 19 const struct tm *restrict); 20 time_t time(time_t *timer); 21 .fi 22 .SH DESCRIPTION 23 The time.h header defines the following macros: 24 25 .B NULL 26 27 An implementation-defined null pointer constant, 28 identical to the one defined in stddef.h. 29 30 .B CLOCKS_PER_SEC 31 32 The number of clock ticks per second, 33 used to convert the value returned by 34 .BR clock () 35 to seconds. Its type is 36 .IR clock_t . 37 38 The time.h header defines the types 39 .BR clock_t , 40 .BR size_t , 41 and 42 .BR time_t . 43 44 The time.h header declares the 45 .B tm 46 structure, 47 which holds a broken-down representation of time 48 and contains at least the following members: 49 50 .nf 51 int tm_sec Seconds [0,60] 52 int tm_min Minutes [0,59] 53 int tm_hour Hour [0,23] 54 int tm_mday Day of month [1,31] 55 int tm_mon Month of year [0,11] 56 int tm_year Years since 1900 57 int tm_wday Day of week [0,6] (Sunday = 0) 58 int tm_yday Day of year [0,365] 59 int tm_isdst Daylight Savings flag 60 .fi 61 62 The members of the 63 .I tm 64 structure are: 65 .TP 10 66 tm_sec 67 Seconds elapsed after the minute, normally 0 to 59, 68 but up to 60 to accommodate leap seconds. 69 .TP 70 tm_min 71 Minutes elapsed after the hour, in the range 0 to 59. 72 .TP 73 tm_hour 74 Hours elapsed since midnight, in the range 0 to 23. 75 .TP 76 tm_mday 77 The calendar day of the month, in the range 1 to 31. 78 .TP 79 tm_mon 80 Months elapsed since January, in the range 0 to 11. 81 .TP 82 tm_year 83 Years elapsed since 1900. 84 .TP 85 tm_wday 86 Days elapsed since Sunday, in the range 0 to 6. 87 .TP 88 tm_yday 89 Days elapsed since January 1st, in the range 0 to 365. 90 .TP 91 tm_isdst 92 A flag indicating whether daylight saving time applies. 93 Positive if in effect, zero if not, and negative if unknown. 94 .SH STANDARDS 95 ISO/IEC 9899:1999 Section 7.23.1 Paragraph 1,2,3,4 96 .SH SEE ALSO 97 .BR clock (3) 98 .BR ctime (3) 99 .BR difftime (3) 100 .BR strftime (3) 101 .BR time (3)