1TIMERADD(3) Linux Programmer's Manual TIMERADD(3)
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6 timeradd, timersub, timercmp, timerclear, timerisset - timeval opera‐
7 tions
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10 #include <sys/time.h>
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12 void timeradd(struct timeval *a, struct timeval *b,
13 struct timeval *res);
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15 void timersub(struct timeval *a, struct timeval *b,
16 struct timeval *res);
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18 void timerclear(struct timeval *tvp);
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20 int timerisset(struct timeval *tvp);
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22 int timercmp(struct timeval *a, struct timeval *b, CMP);
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24 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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26 All functions shown above:
27 Since glibc 2.19:
28 _DEFAULT_SOURCE
29 Glibc 2.19 and earlier:
30 _BSD_SOURCE
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33 The macros are provided to operate on timeval structures, defined in
34 <sys/time.h> as:
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36 struct timeval {
37 time_t tv_sec; /* seconds */
38 suseconds_t tv_usec; /* microseconds */
39 };
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41 timeradd() adds the time values in a and b, and places the sum in the
42 timeval pointed to by res. The result is normalized such that
43 res->tv_usec has a value in the range 0 to 999,999.
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45 timersub() subtracts the time value in b from the time value in a, and
46 places the result in the timeval pointed to by res. The result is nor‐
47 malized such that res->tv_usec has a value in the range 0 to 999,999.
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49 timerclear() zeros out the timeval structure pointed to by tvp, so that
50 it represents the Epoch: 1970-01-01 00:00:00 +0000 (UTC).
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52 timerisset() returns true (nonzero) if either field of the timeval
53 structure pointed to by tvp contains a nonzero value.
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55 timercmp() compares the timer values in a and b using the comparison
56 operator CMP, and returns true (nonzero) or false (0) depending on the
57 result of the comparison. Some systems (but not Linux/glibc), have a
58 broken timercmp() implementation, in which CMP of >=, <=, and == do not
59 work; portable applications can instead use
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61 !timercmp(..., <)
62 !timercmp(..., >)
63 !timercmp(..., !=)
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66 timerisset() and timercmp() return true (nonzero) or false (0).
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69 No errors are defined.
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72 Not in POSIX.1. Present on most BSD derivatives.
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75 gettimeofday(2), time(7)
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78 This page is part of release 5.10 of the Linux man-pages project. A
79 description of the project, information about reporting bugs, and the
80 latest version of this page, can be found at
81 https://www.kernel.org/doc/man-pages/.
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85Linux 2017-09-15 TIMERADD(3)