Linux get millisecond-level time

In software design, time processing is often used to calculate the execution time of statements and functions. In this case, time must be accurate to milliseconds or even a subtle time.

 

Int gettimeofday (struct timeval *TV, Struct timezone *TZ);

Int settimeofday (const struct timeval *TV , Const struct timezone *TZ);

 

Struct timeval {

Time_t TV _sec;/* seconds */

Suseconds_t TV _usec;/* microseconds */

};

 

Struct timezone {

Int tz_minuteswest;/* minutes west of Greenwich */

Int tz_dsttime;/* type of DST correction */

};

 

The following is a simple example for statistics.ProgramExecution time:

...

Struct timeval t_start, t_end;

Long cost_time = 0;

 

// Get start time

Gettimeofday (& t_start, null );

Printf ("Start Time: % LD us", t_start. TV _usec );

 

// Some operation

...

 

// Get End Time

Gettimeofday (& t_end, null );

Printf ("End Time: % LD us", t_end. TV _usec );

 

// Calculate Time Slot

Cost_time = t_end. TV _usec-t_start. TV _usec;

Printf ("cost time: % LD us", cost_time );

...

 

Output:

Start Time: 438061 us

End Time: 459867 us

Cost time: 21806 us

 

Demo:

# Include <stdio. h> # Include <Stdlib. h> # Include <Sys/time. h> Int Main ( Int Argc, Char *Argv []) {printf (  "  Hello, world! \ N  "  );  Struct  Timeval tvafter, tvpre;  Struct  Timezone TZ;  Int Sum = 0  ;  Int I = 0  ; Gettimeofday ( & Tvpre ,&Tz );  For (I = 0 ; I < 100000000 ; I ++ ) {Sum + = I;} gettimeofday ( & Tvafter ,& Tz); printf (  "  Sum = % d elapsed time: % d \ n  " , Sum, (tvafter. TV _sec-tvpre. TV _sec )* 1000 + (Tvafter. TV _usec-tvpre. TV _usec )/ 1000  ); Return  Exit_success ;}