include #include <stdio.h> int GetTime() { struct timespec tsp; clock_gettime(CLOCK_REALTIME, &tsp); //Call clock_gettime to fill tsp fprintf(stdout, "time=%d.%d\n", tsp.tv_sec, tsp.tv_nsec); fflush(stdout); } I am trying to compile the above code but it keeps throwing the error: time.c: In function ‘GetTime’: time.c:12:4: warning: implicit declaration of function ‘clock_gettime’ [-Wimplicit-function-declaration] time.c:12:18: error: ‘CLOCK_REALTIME’ undeclared (first use in this function) time.c:12:18: note: each undeclared identifier is reported only once for each function it appears in time.c:14:4: warning: format ‘%d’ expects argument of type ‘int’, but argument 3 has type ‘__time_t’ [-Wformat] time.c:14:4: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘long int’ [-Wformat] I have tried compiling with -lrt flag and -std=gnu99. Nothing works.