projects / thirdparty / man-pages.git / blame
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1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| 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| 13 | .\" manual page may be incorrect or out-of-date.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 | .\" References consulted: | |
| 24 | .\" Linux libc source code | |
| 25 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
| 26 | .\" 386BSD man pages | |
| 27 | .\" Modified Sat Jul 24 19:48:17 1993 by Rik Faith (faith@cs.unc.edu) | |
| e797c3a0 | 28 | .TH DIFFTIME 3 2002-02-28 "GNU" "Linux Programmer's Manual" |
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29 | .SH NAME |
| 30 | difftime \- calculate time difference | |
| 31 | .SH SYNOPSIS | |
| 32 | .nf | |
| 33 | .B #include <time.h> | |
| 34 | .sp | |
| 35 | .BI "double difftime(time_t " time1 ", time_t " time0 ); | |
| 36 | .fi | |
| 37 | .SH DESCRIPTION | |
| 63aa9df0 | 38 | The \fBdifftime\fP() function returns the number of seconds elapsed |
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39 | between time \fItime1\fP and time \fItime0\fP, represented as a double. |
| 40 | The two times are specified in calendar time, which represents the time | |
| 41 | elapsed since the Epoch | |
| 42 | (00:00:00 on January 1, 1970, Coordinated Universal Time (UTC)). | |
| 43 | .SH "CONFORMING TO" | |
| b14d4aa5 | 44 | SVID 3, 4.3BSD, ISO 9899 |
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45 | .SH NOTES |
| 46 | This function is required by ANSI C. | |
| 47 | On a POSIX system, time_t is an arithmetic type, and one could just | |
| 48 | define | |
| 49 | .RS | |
| 50 | .nf | |
| e797c3a0 | 51 | |
| 2bc2f479 | 52 | #define difftime(t1,t0) (double)(t1 \- t0) |
| e797c3a0 | 53 | |
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54 | .fi |
| 55 | .RE | |
| 56 | when the possible overflow in the subtraction is not a concern. | |
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57 | On other systems, the data type |
| 58 | .I time_t | |
| 59 | might use some other encoding | |
| 60 | where subtraction doesn't work directly. | |
| 61 | .SH "CONFORMING TO" | |
| 62 | SVID 3, 4.3BSD, POSIX.1-2001. | |
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63 | .SH "SEE ALSO" |
| 64 | .BR date (1), | |
| 65 | .BR gettimeofday (2), | |
| 66 | .BR time (2), | |
| 67 | .BR ctime (3), | |
| 68 | .BR gmtime (3), | |
| 69 | .BR localtime (3) |