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1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
| 2 | .\" | |
| 93015253 | 3 | .\" %%%LICENSE_START(VERBATIM) |
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4 | .\" Permission is granted to make and distribute verbatim copies of this |
| 5 | .\" manual provided the copyright notice and this permission notice are | |
| 6 | .\" preserved on all copies. | |
| 7 | .\" | |
| 8 | .\" Permission is granted to copy and distribute modified versions of this | |
| 9 | .\" manual under the conditions for verbatim copying, provided that the | |
| 10 | .\" entire resulting derived work is distributed under the terms of a | |
| 11 | .\" permission notice identical to this one. | |
| c13182ef | 12 | .\" |
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13 | .\" Since the Linux kernel and libraries are constantly changing, this |
| 14 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
| 15 | .\" responsibility for errors or omissions, or for damages resulting from | |
| 16 | .\" the use of the information contained herein. The author(s) may not | |
| 17 | .\" have taken the same level of care in the production of this manual, | |
| 18 | .\" which is licensed free of charge, as they might when working | |
| 19 | .\" professionally. | |
| c13182ef | 20 | .\" |
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21 | .\" Formatted or processed versions of this manual, if unaccompanied by |
| 22 | .\" the source, must acknowledge the copyright and authors of this work. | |
| 4b72fb64 | 23 | .\" %%%LICENSE_END |
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24 | .\" |
| 25 | .\" References consulted: | |
| 26 | .\" Linux libc source code | |
| 27 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
| 28 | .\" 386BSD man pages | |
| 29 | .\" Modified Sat Jul 24 19:48:17 1993 by Rik Faith (faith@cs.unc.edu) | |
| 460495ca | 30 | .TH DIFFTIME 3 2015-08-08 "GNU" "Linux Programmer's Manual" |
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31 | .SH NAME |
| 32 | difftime \- calculate time difference | |
| 33 | .SH SYNOPSIS | |
| 34 | .nf | |
| 35 | .B #include <time.h> | |
| 68e4db0a | 36 | .PP |
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37 | .BI "double difftime(time_t " time1 ", time_t " time0 ); |
| 38 | .fi | |
| 39 | .SH DESCRIPTION | |
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40 | The |
| 41 | .BR difftime () | |
| 42 | function returns the number of seconds elapsed | |
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43 | between time \fItime1\fP and time \fItime0\fP, represented as a |
| 44 | .IR double . | |
| f49c451a | 45 | Each of the times is specified in calendar time, which means its |
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46 | value is a measurement (in seconds) relative to the |
| 47 | Epoch, 1970-01-01 00:00:00 +0000 (UTC). | |
| 51f37626 | 48 | .SH ATTRIBUTES |
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49 | For an explanation of the terms used in this section, see |
| 50 | .BR attributes (7). | |
| 51 | .TS | |
| 52 | allbox; | |
| 53 | lb lb lb | |
| 54 | l l l. | |
| 55 | Interface Attribute Value | |
| 56 | T{ | |
| 51f37626 | 57 | .BR difftime () |
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58 | T} Thread safety MT-Safe |
| 59 | .TE | |
| 47297adb | 60 | .SH CONFORMING TO |
| 75ac82b9 | 61 | POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD. |
| fea681da | 62 | .SH NOTES |
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63 | On a POSIX system, |
| 64 | .I time_t | |
| f5f9a30c | 65 | is an arithmetic type, and one could just |
| fea681da | 66 | define |
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67 | .PP |
| 68 | .in +4n | |
| 69 | .EX | |
| 2bc2f479 | 70 | #define difftime(t1,t0) (double)(t1 \- t0) |
| b9c93deb | 71 | .EE |
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72 | .in |
| 73 | .PP | |
| fea681da | 74 | when the possible overflow in the subtraction is not a concern. |
| 47297adb | 75 | .SH SEE ALSO |
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76 | .BR date (1), |
| 77 | .BR gettimeofday (2), | |
| 78 | .BR time (2), | |
| 79 | .BR ctime (3), | |
| 80 | .BR gmtime (3), | |
| 81 | .BR localtime (3) |