1timeradd(3)                Library Functions Manual                timeradd(3)
2
3
4

NAME

6       timeradd,  timersub,  timercmp, timerclear, timerisset - timeval opera‐
7       tions
8

LIBRARY

10       Standard C library (libc, -lc)
11

SYNOPSIS

13       #include <sys/time.h>
14
15       void timeradd(struct timeval *a, struct timeval *b,
16                     struct timeval *res);
17       void timersub(struct timeval *a, struct timeval *b,
18                     struct timeval *res);
19
20       void timerclear(struct timeval *tvp);
21       int timerisset(struct timeval *tvp);
22
23       int timercmp(struct timeval *a, struct timeval *b, CMP);
24
25   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
26
27       All functions shown above:
28           Since glibc 2.19:
29               _DEFAULT_SOURCE
30           glibc 2.19 and earlier:
31               _BSD_SOURCE
32

DESCRIPTION

34       The macros are provided to operate on timeval  structures,  defined  in
35       <sys/time.h> as:
36
37           struct timeval {
38               time_t      tv_sec;     /* seconds */
39               suseconds_t tv_usec;    /* microseconds */
40           };
41
42       timeradd()  adds  the time values in a and b, and places the sum in the
43       timeval pointed  to  by  res.   The  result  is  normalized  such  that
44       res->tv_usec has a value in the range 0 to 999,999.
45
46       timersub()  subtracts the time value in b from the time value in a, and
47       places the result in the timeval pointed to by res.  The result is nor‐
48       malized such that res->tv_usec has a value in the range 0 to 999,999.
49
50       timerclear() zeros out the timeval structure pointed to by tvp, so that
51       it represents the Epoch: 1970-01-01 00:00:00 +0000 (UTC).
52
53       timerisset() returns true (nonzero) if  either  field  of  the  timeval
54       structure pointed to by tvp contains a nonzero value.
55
56       timercmp()  compares  the  timer values in a and b using the comparison
57       operator CMP, and returns true (nonzero) or false (0) depending on  the
58       result  of  the comparison.  Some systems (but not Linux/glibc), have a
59       broken timercmp() implementation, in which CMP of >=, <=, and == do not
60       work; portable applications can instead use
61
62           !timercmp(..., <)
63           !timercmp(..., >)
64           !timercmp(..., !=)
65

RETURN VALUE

67       timerisset() and timercmp() return true (nonzero) or false (0).
68

ERRORS

70       No errors are defined.
71

STANDARDS

73       None.
74

HISTORY

76       BSD.
77

SEE ALSO

79       gettimeofday(2), time(7)
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83Linux man-pages 6.05              2023-03-30                       timeradd(3)
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