| .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| .\" |
| .\" %%%LICENSE_START(VERBATIM) |
| .\" Permission is granted to make and distribute verbatim copies of this |
| .\" manual provided the copyright notice and this permission notice are |
| .\" preserved on all copies. |
| .\" |
| .\" Permission is granted to copy and distribute modified versions of this |
| .\" manual under the conditions for verbatim copying, provided that the |
| .\" entire resulting derived work is distributed under the terms of a |
| .\" permission notice identical to this one. |
| .\" |
| .\" Since the Linux kernel and libraries are constantly changing, this |
| .\" manual page may be incorrect or out-of-date. The author(s) assume no |
| .\" responsibility for errors or omissions, or for damages resulting from |
| .\" the use of the information contained herein. The author(s) may not |
| .\" have taken the same level of care in the production of this manual, |
| .\" which is licensed free of charge, as they might when working |
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| .\" Formatted or processed versions of this manual, if unaccompanied by |
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| .\" %%%LICENSE_END |
| .\" |
| .\" References consulted: |
| .\" Linux libc source code |
| .\" 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 2021-03-22 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| difftime \- calculate time difference |
| .SH SYNOPSIS |
| .nf |
| .B #include <time.h> |
| .PP |
| .BI "double difftime(time_t " time1 ", time_t " time0 ); |
| .fi |
| .SH DESCRIPTION |
| The |
| .BR difftime () |
| 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). |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lbx lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR difftime () |
| T} Thread safety MT-Safe |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| POSIX.1-2001, POSIX.1-2008, C89, C99, 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 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), |
| .BR time (2), |
| .BR ctime (3), |
| .BR gmtime (3), |
| .BR localtime (3) |
