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Name

Synopsis

#include <sys/time.h>void timeradd(struct timeval *a, struct timeval *b, 
            struct timeval *res);void timersub(struct timeval *a, struct
timeval *b,              struct timeval *res);void timerclear(struct timeval
*tvp);int timerisset(struct timeval *tvp);int timercmp(struct timeval *a,
struct timeval *b, CMP);

Feature Test Macro Requirements for glibc (see feature_test_macros(7) ):

All functions shown above: _BSD_SOURCE

Description

struct timeval {
    time_t      tv_sec;     /* seconds */
    suseconds_t tv_usec;    /* microseconds */
};

timeradd() adds the time values in a and b, and places the sum in the timeval pointed to by res. The result is normalized such that res->tv_usec has a value in the range 0 to 999,999.

timersub() subtracts the time value in b from the time value in a, and places the result in the timeval pointed to by res. The result is normalized such that res->tv_usec has a value in the range 0 to 999,999.

timerclear() zeros out the timeval structure pointed to by tvp, so that it represents the Epoch: 1970-01-01 00:00:00 +0000 (UTC).

timerisset() returns true (nonzero) if either field of the timeval structure pointed to by tvp contains a nonzero value.

timercmp() compares the timer values in a and b using the comparison operator CMP, and returns true (nonzero) or false (0) depending on the result of the comparison. Some systems (but not Linux/glibc), have a broken timercmp() implementation, in which CMP of >=, <=, and == do not work; portable applications can instead use

!timercmp(..., <)
!timercmp(..., >)
!timercmp(..., !=)

Return Value

Errors

Conforming to

See Also

Colophon

Table of Contents

• Name
• Synopsis
• Description
• Return Value
• Errors
• Conforming to
• See Also
• Colophon