projects / thirdparty / man-pages.git / blame
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1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| 2 | .\" | |
| 5fbde956 | 3 | .\" SPDX-License-Identifier: Linux-man-pages-copyleft |
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4 | .\" |
| 5 | .\" References consulted: | |
| 6 | .\" Linux libc source code | |
| 7 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
| 8 | .\" 386BSD man pages | |
| 9 | .\" Modified Sat Jul 24 19:48:17 1993 by Rik Faith (faith@cs.unc.edu) | |
| 4c1c5274 | 10 | .TH difftime 3 (date) "Linux man-pages (unreleased)" |
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11 | .SH NAME |
| 12 | difftime \- calculate time difference | |
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13 | .SH LIBRARY |
| 14 | Standard C library | |
| 15 | .RI ( libc ", " \-lc ) | |
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16 | .SH SYNOPSIS |
| 17 | .nf | |
| 18 | .B #include <time.h> | |
| 68e4db0a | 19 | .PP |
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20 | .BI "double difftime(time_t " time1 ", time_t " time0 ); |
| 21 | .fi | |
| 22 | .SH DESCRIPTION | |
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23 | The |
| 24 | .BR difftime () | |
| 25 | function returns the number of seconds elapsed | |
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26 | between time \fItime1\fP and time \fItime0\fP, represented as a |
| 27 | .IR double . | |
| f49c451a | 28 | Each of the times is specified in calendar time, which means its |
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29 | value is a measurement (in seconds) relative to the |
| 30 | Epoch, 1970-01-01 00:00:00 +0000 (UTC). | |
| 51f37626 | 31 | .SH ATTRIBUTES |
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32 | For an explanation of the terms used in this section, see |
| 33 | .BR attributes (7). | |
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34 | .ad l |
| 35 | .nh | |
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36 | .TS |
| 37 | allbox; | |
| c466875e | 38 | lbx lb lb |
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39 | l l l. |
| 40 | Interface Attribute Value | |
| 41 | T{ | |
| 51f37626 | 42 | .BR difftime () |
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43 | T} Thread safety MT-Safe |
| 44 | .TE | |
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45 | .hy |
| 46 | .ad | |
| 47 | .sp 1 | |
| 3113c7f3 | 48 | .SH STANDARDS |
| 75ac82b9 | 49 | POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD. |
| fea681da | 50 | .SH NOTES |
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51 | On a POSIX system, |
| 52 | .I time_t | |
| f5f9a30c | 53 | is an arithmetic type, and one could just |
| fea681da | 54 | define |
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55 | .PP |
| 56 | .in +4n | |
| 57 | .EX | |
| 2bc2f479 | 58 | #define difftime(t1,t0) (double)(t1 \- t0) |
| b9c93deb | 59 | .EE |
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60 | .in |
| 61 | .PP | |
| fea681da | 62 | when the possible overflow in the subtraction is not a concern. |
| 47297adb | 63 | .SH SEE ALSO |
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64 | .BR date (1), |
| 65 | .BR gettimeofday (2), | |
| 66 | .BR time (2), | |
| 67 | .BR ctime (3), | |
| 68 | .BR gmtime (3), | |
| 69 | .BR localtime (3) |