在OSX上编译的ctime和time警告

extras.c:15: warning: implicit declaration of function ‘time’
extras.c: In function ‘outlog’:
extras.c:363: warning: implicit declaration of function ‘ctime’

RANDNUMGEN = gsl_rng_alloc(gsl_rng_taus);
long t1;
(void) time(&t1);

if (LOG==NULL) { LOG=stdout;}

TVAL = time(NULL);
char* TIMESTRING = ctime(&TVAL);

time

ctime