time.h.3 (2308B)
1 .TH time.h 3 2 .SH NAME 3 time.h - time types 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 It expands to an implementation-defined null pointer constant, 28 as defined in stddef.h header. 29 30 .B CLOCKS_PER_SEC 31 32 A number used to convert the value returned by the 33 .BR clock () 34 function into seconds. The value is an expression with type 35 clock_t. 36 37 The time.h header defines the following types: 38 .BR clock_t , 39 .BR size_t , 40 .BR time_t . 41 42 The 43 time.h header declares the 44 .B tm 45 structure, 46 which includes at least the following members: 47 48 .nf 49 int tm_sec Seconds[0,60] 50 int tm_min Minutes[0,59] 51 int tm_hour Hour[0,23] 52 int tm_mday Day of month [1,31] 53 int tm_mon Month of year [0,11] 54 int tm_year Years since 1900 55 int tm_wday Day of week [0,6] (Sunday =0) 56 int tm_yday Day of year [0,365] 57 int tm_isdst Daylight Savings flag 58 .fi 59 60 The members of the 61 .I tm 62 structure are: 63 .TP 10 64 tm_sec 65 The number of seconds after the minute, normally in the range 0 to 59, 66 but can be up to 60 to allow for leap seconds. 67 .TP 68 tm_min 69 The number of minutes after the hour, in the range 0 to 59. 70 .TP 71 tm_hour 72 The number of hours past midnight, in the range 0 to 23. 73 .TP 74 tm_mday 75 The day of the month, in the range 1 to 31. 76 .TP 77 tm_mon 78 The number of months since January, in the range 0 to 11. 79 .TP 80 tm_year 81 The number of years since 1900. 82 .TP 83 tm_wday 84 The number of days since Sunday, in the range 0 to 6. 85 .TP 86 tm_yday 87 The number of days since January 1, in the range 0 to 365. 88 .TP 89 tm_isdst 90 A flag that indicates whether daylight saving time is 91 in effect at the time described. 92 The value is positive if daylight saving time is in 93 effect, zero if it is not, and negative if the information is not 94 available. 95 .SH STANDARDS 96 ISO/IEC 9899:1999 Section 7.23.1 Paragraph 1,2,3,4 97 .SH SEE ALSO 98 .BR clock (3) 99 .BR ctime (3) 100 .BR difftime (3) 101 .BR strftime (3) 102 .BR time (3)