```cpp
#include?<sys/uio.h>
ssize_t?readv(int?fd,?const?struct?iovec?*iov,?int?iovcnt);
ssize_t?writev(int?fd,?const?struct?iovec?*iov,?int?iovcnt);
struct?iovec?{
????void?*iov_base;??/*?Starting?address?*/
size_t?iov_len;??/*?Number?of?bytes?to?transfer?*/
};
The?readv()?system?call?reads?iovcnt?buffers?from?the?file?associated?with?the?file?descriptor?fd?into?the?buffers?described?by?iov?("scatter?input").
The?writev()?system?call?writes?iovcnt?buffers?of?data?described?by?iov?to?the?file?associated?with?the?file?descriptor?fd?("gather?output").
```
```cpp
????#include?<unistd.h>
????#include?<sys/uio.h>
????#include?<stdio.h>
????#include?<fcntl.h>
????
????int?main(int?argc,?char?*argv[])
????{
???? ssize_t?iSize;
???? char?acBuf1[9];
???? char?acBuf2[9];
???? struct?iovec?iov[2];
????
???? int?iFd1?=?open(argv[1],?O_RDONLY);
???? int?iFd2?=?open(argv[2],?O_RDONLY);
???? int?iFd3?=?open(argv[3],?O_WRONLY);
????
???? iSize?=?read(iFd1,?acBuf1,?sizeof(acBuf1));
???? iSize?=?read(iFd2,?acBuf2,?sizeof(acBuf2));
????
???? iov[0].iov_base?=?acBuf1;
???? iov[0].iov_len?=?sizeof(acBuf1);
???? iov[1].iov_base?=?acBuf2;
???? iov[1].iov_len?=?sizeof(acBuf2);
????
???? iSize?=?writev(iFd3,?iov,?2);
????
???? close(iFd1);
???? close(iFd2);
???? close(iFd3);
????
???? return?0;
????}
????
```
建立3个文件（test1，?test2，?test3）
test1写入12345
test2写入asdfghi
test3为空
运行
./a.out?test1?test2?test3
writev/readv
原文：http://www.cnblogs.com/mdgsf/p/5208884.html
