c++ - What could be the format specifier for the below program? -

void task(task100ms_raster) {     int a,b,c;     struct timespec start, stop;     uint32 starttime, stoptime;     uint32 duration100ms;      if( clock_gettime( clock_realtime, &start) == -1 ) {        perror( "clock gettime" );     }      starttime =start.tv_sec + 0.0000001 * start.tv_nsec;     printf("start time %lu", starttime);      printf("value %d",c);     printf("etas1\n");     if( (stoptime = clock_gettime( clock_realtime, &stop)) == -1 )     {       perror( "clock gettime" );     }     stoptime =  stop.tv_sec + 0.0000001 * stop.tv_nsec;     printf("stop time %lu", stoptime);      duration100ms = stoptime -starttime;     printf( "time difference is= %lu\n", duration100ms ); } 

i created timer calculating start time, stop time , difference between time. confused format specifier start time, stop time , suration100ms. struct timespec start, stop; of type http://www.qnx.com/developers/docs/6.3.0sp3/neutrino/lib_ref/t/timespec.html correct format specifiers results. guide me.

you're doing floating-point calculation compute number of seconds, storing result in integer:

starttime = start.tv_sec + 0.0000001 * start.tv_nsec; 

this truncate result whole integers. should make starttime double, , print such:

double starttime = start.tv_sec + 1e-9 * start.tv_nsec;  printf("start time %f\n", starttime); 

i think it's better precision, convert float when compute difference:

double duration = stoptime.tv_sec - starttime.tv_sec +                   1e-9 * (stoptime.tv_nsec - starttime.tv_nsec); 

if must have duration integer number in units of 100 ms, do:

duration = 10000 * (stoptime.tv_sec - starttime.tv_sec) +             (stoptime.tv_nsec - starttime.tv_nsec) / 100000000;