readv writev 簡介 一次讀寫多個緩衝區

一個小例子說明函數使用:

結構說明:

struct iovec {
    void * iov_base //緩衝區地址
    size_t iov_len  //緩衝區輸入/輸出長度
}

#include "util.h"
#include <sys/uio.h>
 
 
int main(int argc , char **argv)
{
    struct iovec v[2]; 
 
    char buf1[] = "nihao";
    char buf2[] = "fuck me";
    v[0].iov_base = buf1;
    v[0].iov_len = 3;       // 輸入/輸出 3個字節
    v[1].iov_base = buf2;
    v[1].iov_len = 4;       //輸入/輸出 4個字節
    int n  = writev(1,v,2);
    printf("\n write bytes:%d\n" , n);
 
 
    puts("reading from stdin");
    n = readv(0,v,2);
    printf("read bytes:%d\n",n);
    printf("buf1:%s\n" ,buf1);
    printf("buf2:%s\n",buf2);
 
    return 0;
}