1 .\" Copyright (c) 2007 by Michael Kerrisk <mtk.manpages@gmail.com>
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25 .\" 2007-07-31, mtk, Created
27 .TH TIMERADD 3 2021-03-22 "Linux" "Linux Programmer's Manual"
29 timeradd, timersub, timercmp, timerclear, timerisset \- timeval operations
32 .B #include <sys/time.h>
34 .BI "void timeradd(struct timeval *" a ", struct timeval *" b ,
35 .BI " struct timeval *" res );
36 .BI "void timersub(struct timeval *" a ", struct timeval *" b ,
37 .BI " struct timeval *" res );
39 .BI "void timerclear(struct timeval *" tvp );
40 .BI "int timerisset(struct timeval *" tvp );
42 .BI "int timercmp(struct timeval *" a ", struct timeval *" b ", " CMP );
46 Feature Test Macro Requirements for glibc (see
47 .BR feature_test_macros (7)):
50 All functions shown above:
54 Glibc 2.19 and earlier:
58 The macros are provided to operate on
60 structures, defined in
67 time_t tv_sec; /* seconds */
68 suseconds_t tv_usec; /* microseconds */
74 adds the time values in
78 and places the sum in the
82 The result is normalized such that
84 has a value in the range 0 to 999,999.
87 subtracts the time value in
89 from the time value in
91 and places the result in the
95 The result is normalized such that
97 has a value in the range 0 to 999,999.
102 structure pointed to by
104 so that it represents the Epoch: 1970-01-01 00:00:00 +0000 (UTC).
107 returns true (nonzero) if either field of the
109 structure pointed to by
111 contains a nonzero value.
114 compares the timer values in
118 using the comparison operator
120 and returns true (nonzero) or false (0) depending on
121 the result of the comparison.
122 Some systems (but not Linux/glibc),
126 .\" HP-UX, Tru64, Irix have a definition like:
127 .\"#define timercmp(tvp, uvp, cmp) \
128 .\" ((tvp)->tv_sec cmp (uvp)->tv_sec || \
129 .\" (tvp)->tv_sec == (uvp)->tv_sec && (tvp)->tv_usec cmp (uvp)->tv_usec)
138 portable applications can instead use
147 return true (nonzero) or false (0).
149 No errors are defined.
152 Present on most BSD derivatives.
154 .BR gettimeofday (2),