a C threadPool
add the .h and .c files to your project,remember to make sure you compile you project with pthread.h
//ThreadPool_init(int num) use for create a new threadpool ,the number of this threadpool cover is the num
//ThreadPool_work_in(ThreadPool* th) use for add new work to your threapool
//ThreadPool_wait(ThreadPool* th) use for wait all the tasks finish
//ThreadPool_destroy(ThreadPool* th) use for destroy your threadpool