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author | dkf <donal.k.fellows@manchester.ac.uk> | 2009-02-24 21:04:58 (GMT) |
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committer | dkf <donal.k.fellows@manchester.ac.uk> | 2009-02-24 21:04:58 (GMT) |
commit | d24c35f276199a428012749034360a0ab17c00da (patch) | |
tree | bd89a06d093bc6aed00d0c588a506836a2576c5c /doc/clock.n | |
parent | b51f251bd053d6532d178b3f1b101d5cfd15f610 (diff) | |
download | tcl-d24c35f276199a428012749034360a0ab17c00da.zip tcl-d24c35f276199a428012749034360a0ab17c00da.tar.gz tcl-d24c35f276199a428012749034360a0ab17c00da.tar.bz2 |
General minor documentation improvements.
Diffstat (limited to 'doc/clock.n')
-rw-r--r-- | doc/clock.n | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/doc/clock.n b/doc/clock.n index f4c3805..56a139e 100644 --- a/doc/clock.n +++ b/doc/clock.n @@ -161,12 +161,14 @@ the environment variable \fBTZ\fR. .IP [3] on Windows systems, the time zone settings from the Control Panel. .RE +.PP If none of these is present, the C \fBlocaltime\fR and \fBmktime\fR functions are used to attempt to convert times between local and Greenwich. On 32-bit systems, this approach is likely to have bugs, particularly for times that lie outside the window (approximately the years 1902 to 2037) that can be represented in a 32-bit integer. .SH "CLOCK ARITHMETIC" +.PP The \fBclock add\fR command performs clock arithmetic on a value (expressed as nominal seconds from the epoch time of 1 January 1970, 00:00 UTC) given as its first argument. The remaining arguments (other than the @@ -275,6 +277,7 @@ years as they are when adding/subtracting days and weeks. If multiple \fIcount unit\fR pairs are present on the command, they are evaluated consecutively, from left to right. .SH "HIGH RESOLUTION TIMERS" +.PP Most of the subcommands supported by the \fBclock\fR command deal with times represented as a count of seconds from the epoch time, and this is the representation that \fBclock seconds\fR returns. There are three exceptions, @@ -289,6 +292,7 @@ epoch; it is simply intended to be the most precise interval timer available, and is intended only for relative timing studies such as benchmarks. .SH "FORMATTING TIMES" +.PP The \fBclock format\fR command produces times for display to a user or writing to an external medium. The command accepts times that are expressed in seconds from the epoch time of 1 January 1970, 00:00 UTC, @@ -327,6 +331,7 @@ platforms that do not define a user selection of date and time formats separate from \fBLC_TIME\fR, \fB\-locale\fR \fBsystem\fR is synonymous with \fB\-locale\fR \fBcurrent\fR. .SH "SCANNING TIMES" +.PP The \fBclock scan\fR command accepts times that are formatted as strings and converts them to counts of seconds from the epoch time of 1 January 1970, 00:00 UTC. It normally takes a \fB\-format\fR @@ -449,6 +454,7 @@ If this situation occurs, the first occurrence of the time is chosen. time zone when converting local times. This caveat does not apply to UTC times.) .SH "FORMAT GROUPS" +.PP The following format groups are recognized by the \fBclock scan\fR and \fBclock format\fR commands. .TP @@ -738,6 +744,7 @@ character. Synonymous with .QW "\fB%a %b %e %H:%M:%S %Z %Y\fR" . .SH "TIME ZONES" +.PP When the \fBclock\fR command is processing a local time, it has several possible sources for the time zone to use. In order of preference, they are: @@ -825,10 +832,12 @@ rules change again. Any other time zone string is processed by prefixing a colon and attempting to use it as a location name, as above. .SH "LOCALIZATION" +.PP Developers wishing to localize the date and time formatting and parsing are referred to \fIhttp://tip.tcl.tk/173\fR for a specification. .SH "FREE FORM SCAN" +.PP If the \fBclock scan\fR command is invoked without a \fB\-format\fR option, then it requests a \fIfree-form scan.\fR \fI This form of scan is deprecated.\fR The reason for the deprecation |