????send??????
????#include <sys/types.h>
????#include <sys/socket.h>
????ssize_t send(int s??const void*buf??size_t len??int flags);
????send????????????buf?е??С?len????????????????????????s????flasg???????????????????е??????recv()????￡????????????????????????????
?????????????????buf?е????????send????????????????????????????????send()?????????send()??????С??len??????滺?????????в?????????з????????????????·???????????????????????????????????????buf?е?????λ?y????????????С???????????????????
??????send()????-1??????????

????????send()???????????????????????????????????????connect()?????????????????????????????send??write????????????????flag????flag?0???send()??write()???????????send(s??buf??len??flags)??sendto(s??buf??len??flags??NULL??0)??????
????readv????:
????#include <sys/uio.h>
????ssize_t readv(int s??const struct iovec*vector??int count);
????read()??????????????????????readv?????????????????s?ж??count???????????????????vector?С???????????????????????????????-1???????????
???????е????vector???????????????struct iover?????<sys/uio.h>???壺
????1 struct iovec
????2 {
????3     void*iov_base;                             // ??????????????
????4     size_t iov_len;                             // ??С????????λ
????5 }

?????????readv???????????iovec??iov_len????????????iov_len?С?????vector???????vector????棬??Сcount?????????????????????????????????

????writev??????
????#include <sys/uio.h>
????ssize_t writev(int s??const struct iovec*vector??int count);
????//// ???????ú?readv???
???????
?????±??????????????????????O????????????????