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-rw-r--r--man3/difftime.328
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),