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Diffstat (limited to '')
| -rw-r--r-- | man3/difftime.3 | 28 |
1 files changed, 9 insertions, 19 deletions
diff --git a/man3/difftime.3 b/man3/difftime.3 index e1cd34f..d1e392e 100644 --- a/man3/difftime.3 +++ b/man3/difftime.3 @@ -8,7 +8,7 @@ .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) .\" 386BSD man pages .\" Modified Sat Jul 24 19:48:17 1993 by Rik Faith (faith@cs.unc.edu) -.TH difftime 3 2023-07-20 "Linux man-pages 6.05.01" +.TH difftime 3 2023-11-11 "Linux man-pages 6.7" .SH NAME difftime \- calculate time difference .SH LIBRARY @@ -17,7 +17,7 @@ Standard C library .SH SYNOPSIS .nf .B #include <time.h> -.PP +.P .BI "double difftime(time_t " time1 ", time_t " time0 ); .fi .SH DESCRIPTION @@ -26,9 +26,13 @@ The function returns the number of seconds elapsed between time \fItime1\fP and time \fItime0\fP, represented as a .IR double . -Each of the times is specified in calendar time, which means its -value is a measurement (in seconds) relative to the -Epoch, 1970-01-01 00:00:00 +0000 (UTC). +Each time is a count of seconds. +.P +.I difftime(b,\~a) +acts like +.I (b\-a) +except that the result does not overflow and is rounded to +.IR double . .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). @@ -43,24 +47,10 @@ T{ .BR difftime () T} Thread safety MT-Safe .TE -.sp 1 .SH STANDARDS C11, POSIX.1-2008. .SH HISTORY POSIX.1-2001, C89, SVr4, 4.3BSD. -.SH NOTES -On a POSIX system, -.I time_t -is an arithmetic type, and one could just -define -.PP -.in +4n -.EX -#define my_difftime(t1,t0) (double)(t1 \- t0) -.EE -.in -.PP -when the possible overflow in the subtraction is not a concern. .SH SEE ALSO .BR date (1), .BR gettimeofday (2), |