ptheard

add -lptheard with gcc

warning: implicit declaration of function ‘sleep’ [-Wimplicit-function-declaration]
 sleep(1);

http://stackoverflow.com/questions/14818084/what-is-the-proper-include-for-the-function-sleep-in-c

according to man page sleep(3)
http://linux.die.net/man/3/sleep
http://www.gnu.org/software/coreutils/manual/html_node/sleep-invocation.html#sleep-invocation

should add    #include <unistd.h>