readv writev示例程序

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/uio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>

int main()
{
    int ret;
    int fd;
    char str0[6];
    char str1[15];
    struct iovec iov[2];

    fd = open("./tmp", O_RDWR);
    if (fd < 0) {
        perror("open");
        return -1;
    }
#if 0
    read(fd, str0, sizeof(str0));
    printf("%s\n", str0);
    close(fd);
    return 0;
#endif
    memset(str0, 0, sizeof(str0));
    memset(str1, 0, sizeof(str1));
    iov[0].iov_base = str0;
    iov[0].iov_len = sizeof(str0);
    iov[1].iov_base = str1;
    iov[1].iov_len = sizeof(str1);

    ret = readv(fd, iov, 2);
    if (ret < 0) {
        perror("readv");
        close(fd);
        return -1;
    }

    sleep(1);
    printf("...%s\n", str0);
    printf("...%s\n", str1);
    sleep(1);

    ret = writev(STDOUT_FILENO, iov, 2);
    if (ret < 0) {
        perror("writev");
        close(fd);
        return -1;
    }

    close(fd);
    return 0;
}