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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14 | .\" manual page may be incorrect or out-of-date.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) |