How do I measure time in C?
You can use the time.h library, specifically the time and difftime functions:
/* difftime example */#include <stdio.h>#include <time.h>int main (){ time_t start,end; double dif; time (&start); // Do some calculation. time (&end); dif = difftime (end,start); printf ("Your calculations took %.2lf seconds to run.\n", dif ); return 0;}(Example adapted from the difftime webpage linked above.)
Please note that this method can only give seconds worth of accuracy - time_t records the seconds since the UNIX epoch (Jan 1st, 1970).
Sometime it's needed to measure astronomical time rather than CPU time (especially this applicable on Linux):
#include <time.h>double what_time_is_it(){ struct timespec now; clock_gettime(CLOCK_REALTIME, &now); return now.tv_sec + now.tv_nsec*1e-9;}int main() { double time = what_time_is_it(); printf("time taken %.6lf\n", what_time_is_it() - time); return 0;}