douxie7738 2017-10-26 10:53 采纳率: 0%
浏览 271
已采纳

GoLang在字节片的第N行获取字符串

In a personal project I am implementing a function that returns a random line from a long file. For it to work I have to create a function that returns a string at line N, a second function that creates a random number between 0 and lines in file. While I was implementing those I figured it may be more efficient to store the data in byte slices by default, rather than storing them in separate files, which have to be read at run time.

Question: How would I go about implementing a function that returns a string at a random line of the []byte representation of my file.

My function for getting a string from a file:

func atLine(n int) (s string) {
    f, err := os.Open("./path/to/file")
    if err != nil {
        panic("Could not read file.")
    }
    defer f.Close()
    r := bufio.NewReader(f)
    for i := 1; ; i++ {
        line, _, err := r.ReadLine()
        if err != nil {
            break
        }
        if i == n {
            s = string(line[:])
            break
        }
    }
    return s
}

Additional info:

  • Lines are not longer than 50 characters at most
  • Lines have no special characters (although a solution handling those is welcome)
  • Number of lines in the files is known and so the same can be applied for []byte
  • 写回答

2条回答 默认 最新

  • douzhuo6270 2017-10-26 11:19
    关注

    Dealing with just the question part (and not the sanity of this) - you have a []byte and want to get a specific string line from it - the bytes.Reader has no ReadLine method which you will have already noticed.

    You can pass a bytes reader to bufio.NewReader, and gain the ReadLine functionality you are trying to access.

    bytesReader := bytes.NewReader([]byte("test1
    test2
    test3
    "))
    bufReader := bufio.NewReader(bytesReader)
    value1, _, _ := bufReader.ReadLine()
    value2, _, _ := bufReader.ReadLine()
    value3, _, _ := bufReader.ReadLine()
    fmt.Println(string(value1))
    fmt.Println(string(value2))
    fmt.Println(string(value3))
    

    Obviously it is not sensible to ignore the errors, but for the purpose of brevity I do it here.

    https://play.golang.org/p/fRQUfmZQke

    Results:

    test1
    test2
    test3
    

    From here, it is straight forward to fit back into your existing code.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论
查看更多回答(1条)

报告相同问题?

悬赏问题

  • ¥15 wincc已组态的变量过多
  • ¥60 如图:直线与椭圆X轴平行,求直线与椭圆任意一点的相切坐标计算公式
  • ¥50 如何用python使用opencv里的cv::cudacodec::VideoWriter函数对视频进行GPU硬编码
  • ¥100 c#solidworks 二次开发 工程图自动标边线法兰 等折弯尺寸怎么标
  • ¥15 halcon DrawRegion 提示错误
  • ¥15 FastAPI Uvicorn启动显示404
  • ¥15 centos7.9脚本,怎么排除特定的访问记录
  • ¥15 关于#Django#的问题:我的静态文件呢?
  • ¥15 关于CPLEX的问题,请专家解答
  • ¥15 cocos的点击事件 怎么穿透到 原生fragment上。