Linux readv/writev functions

1. Function prototype

#include <sys/uio.h>

ssize_t readv(int filedes, const struct iovec *iov, int iovcnt);

ssize_t writev(int filedes, const struct iovec *iov, int iovcnt);

返回值：
	成功：读入或写出的字节数
	失败：-1
作用：
	readv和writev允许 单个系统调用 读入或写出 自一个或多个缓冲区；
	分散读和集中写

2. Function parameter iovec structure and iovcnt

struct iovec {
    
    
    void     *iov_base;  /* starting address of buffer */
    					/*读入或写出的首地址*/
    size_t   iov_len;    /* size of buffer */
    					/*读入或写出的字节个数*/
};

  iovcnt : the number of iovecs used

It's not easy to organize your likes and attention, which is a great encouragement to me