如何突破遞歸調用

Question

如何分解遞歸如下：

調用GetDirectory("D:\\Engine\\", "102")

預期輸出：D：\\ Engine \\ Type \\ Tone_Id_102
當前，輸出為null。

非常感謝。

private static string GetDirectory(string folderPath, string number)
{
    foreach (string directory in Directory.GetDirectories(folderPath))
    {
        if (directory.Contains(number))
        {
            return directory;
        }

        GetDirectory(directory, number);
    }

    return null;
}

Answer 1

做起來會不會更容易更好

return Directory.EnumerateDirectories(
        folderPath,
        "*",
        SearchOption.AllDirectories)
    .FirstOrDefault(s => s.Contains(number))

或@TimSchmelter建議，

return Directory.EnumerateDirectories(
        folderPath,
        string.Format("*{0}*", number),
        SearchOption.AllDirectories)
    .FirstOrDefault()

Answer 2

我認為您只需要return ：

return GetDirectory(directory, number);

但是，這將迭代foreach一個條目，因此會更好：

private static string GetDirectory(string folderPath, string number)
{
    foreach (string directory in Directory.GetDirectories(folderPath))
    {
        if (directory.Contains(number))
        {
            return directory;
        }

        string result = GetDirectory(directory, number);

        if (!string.IsNullOrEmpty(result))
        {
            return result;
        }
    }

    return null;
}

Answer 3

應該這樣做：

private static string GetDirectory(string folderPath, string number)
{
    foreach (string directory in Directory.GetDirectories(folderPath))
    {
        if (directory.Contains(number))
            return directory;

        var innerDir = GetDirectory(directory, number);
        if (innerDir != null)
            return innerDir;
    }

    return null;
}

Answer 4

這做同樣的事情，我認為它更具可讀性：

Directory.GetDirectories(folderPath, "*.*", SearchOption.AllDirectories)
         .FirstOrDefault(x => x.Contains(number));