projects / apple / libc.git / blame
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1 | .\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl> |
| 2 | .\" | |
| 3 | .\" Permission is granted to make and distribute verbatim copies of this | |
| 4 | .\" manual provided the copyright notice and this permission notice are | |
| 5 | .\" preserved on all copies. | |
| 6 | .\" | |
| 7 | .\" Permission is granted to copy and distribute modified versions of this | |
| 8 | .\" manual under the conditions for verbatim copying, provided that the | |
| 9 | .\" entire resulting derived work is distributed under the terms of a | |
| 10 | .\" permission notice identical to this one | |
| 11 | .\" | |
| 12 | .\" Since the Linux kernel and libraries are constantly changing, this | |
| 13 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
| 14 | .\" responsibility for errors or omissions, or for damages resulting from | |
| 15 | .\" the use of the information contained herein. The author(s) may not | |
| 16 | .\" have taken the same level of care in the production of this manual, | |
| 17 | .\" which is licensed free of charge, as they might when working | |
| 18 | .\" professionally. | |
| 19 | .\" | |
| 20 | .\" Formatted or processed versions of this manual, if unaccompanied by | |
| 21 | .\" the source, must acknowledge the copyright and authors of this work. | |
| 22 | .\" | |
| 23 | .TH TIMEGM 3 2001-12-26 "GNU" "Linux Programmer's Manual" | |
| 24 | .SH NAME | |
| 25 | timegm, timelocal \- inverses for gmtime and localtime | |
| 26 | .SH SYNOPSIS | |
| 27 | .nf | |
| 28 | .B #include <time.h> | |
| 29 | .sp | |
| 30 | .BI "time_t timelocal (struct tm *" tm ); | |
| 31 | .sp | |
| 32 | .BI "time_t timegm (struct tm *" tm ); | |
| 33 | .SH DESCRIPTION | |
| 34 | The functions | |
| 35 | .B timelocal() | |
| 36 | and | |
| 37 | .B timegm() | |
| 38 | are the inverses to | |
| 39 | .BR localtime (3) | |
| 40 | and | |
| 41 | .BR gmtime (3). | |
| 42 | .SH NOTES | |
| 43 | These functions are GNU extensions. | |
| 44 | The | |
| 45 | .B timelocal() | |
| 46 | function is equivalent to the POSIX standard function | |
| 47 | .BR mktime (3). | |
| 48 | There is no reason to ever use it. | |
| 49 | .LP | |
| 50 | For a portable version of | |
| 51 | .BR timegm() , | |
| 52 | set the | |
| 53 | .B TZ | |
| 54 | environment variable to UTC, call | |
| 55 | .B mktime() | |
| 56 | and restore the value of | |
| 57 | .BR TZ . | |
| 58 | Something like | |
| 59 | ||
| 60 | .RS | |
| 61 | .nf | |
| 62 | #include <time.h> | |
| 63 | #include <stdlib.h> | |
| 64 | ||
| 65 | time_t my_timegm (struct tm *tm) { | |
| 66 | time_t ret; | |
| 67 | char *tz; | |
| 68 | ||
| 69 | tz = getenv("TZ"); | |
| 70 | setenv("TZ", "", 1); | |
| 71 | tzset(); | |
| 72 | ret = mktime(tm); | |
| 73 | if (tz) | |
| 74 | setenv("TZ", tz, 1); | |
| 75 | else | |
| 76 | unsetenv("TZ"); | |
| 77 | tzset(); | |
| 78 | return ret; | |
| 79 | } | |
| 80 | .fi | |
| 81 | .RE | |
| 82 | .SH "SEE ALSO" | |
| 83 | .BR gmtime (3), | |
| 84 | .BR localtime (3), | |
| 85 | .BR mktime (3), | |
| 86 | .BR tzset (3) |