C# 获取指定目录下指定排序方式指定后缀指定数量的文件

/// <summary>
/// 按创建时间降序读取指定数目，指定后缀，指定目录下的文件
/// </summary>
/// <param name="path"></param>
/// <param name="searchPattern"></param>
/// <param name="searchOption"></param>
/// <param name="count"></param>
/// <returns></returns>
public static string[] GetFilesByCreationTimeDesc(string path,string searchPattern,SearchOption searchOption,int count)
{
    var query = (from f in Directory.GetFiles(path, searchPattern, searchOption)
                 let fi = new FileInfo(f)
                 orderby fi.CreationTime descending
                 select fi.FullName).Take(count);
    return query.ToArray();
}
/// <summary>
/// 按创建时间升序读取指定数目，指定后缀，指定目录下的文件
/// </summary>
/// <param name="path"></param>
/// <param name="searchPattern"></param>
/// <param name="searchOption"></param>
/// <param name="count"></param>
/// <returns></returns>
public  static string[] GetFilesByCreationTimeAsc(string path, string searchPattern, SearchOption searchOption, int count)
{
    var query = (from f in Directory.GetFiles(path, searchPattern, searchOption)
                 let fi = new FileInfo(f)
                 orderby fi.CreationTime ascending
                 select fi.FullName).Take(count);
    return query.ToArray();
}
/// <summary>
/// 按修改时间降序读取指定数目，指定后缀，指定目录下的文件
/// </summary>
/// <param name="path"></param>
/// <param name="searchPattern"></param>
/// <param name="searchOption"></param>
/// <param name="count"></param>
/// <returns></returns>
public static string[] GetFilesByLastWriteTimeDesc(string path, string searchPattern, SearchOption searchOption, int count)
{
    var query = (from f in Directory.GetFiles(path, searchPattern, searchOption)
                 let fi = new FileInfo(f)
                 orderby fi.CreationTime descending
                 select fi.FullName).Take(count);
    return query.ToArray();
}
/// <summary>
/// 按修改时间升序读取指定数目，指定后缀，指定目录下的文件
/// </summary>
/// <param name="path"></param>
/// <param name="searchPattern"></param>
/// <param name="searchOption"></param>
/// <param name="count"></param>
/// <returns></returns>
public static string[] GetFilesByLastWriteTimeAsc(string path, string searchPattern, SearchOption searchOption, int count)
{
    var query = (from f in Directory.GetFiles(path, searchPattern, searchOption)
                 let fi = new FileInfo(f)
                 orderby fi.CreationTime ascending
                 select fi.FullName).Take(count);
    return query.ToArray();
}
/// <summary>
/// 按文件名称降序读取指定数目，指定后缀，指定目录下的文件
/// </summary>
/// <param name="path"></param>
/// <param name="searchPattern"></param>
/// <param name="searchOption"></param>
/// <param name="count"></param>
/// <returns></returns>
public static string[] GetFilesByNameDesc(string path, string searchPattern, SearchOption searchOption, int count)
{
    var query = (from f in Directory.GetFiles(path, searchPattern, searchOption)
                 let fi = new FileInfo(f)
                 orderby fi.Name ascending
                 select fi.FullName).Take(count);
    return query.ToArray();
}
/// <summary>
/// 按文件名称升序读取指定数目，指定后缀，指定目录下的文件
/// </summary>
/// <param name="path"></param>
/// <param name="searchPattern"></param>
/// <param name="searchOption"></param>
/// <param name="count"></param>
/// <returns></returns>
public static string[] GetFilesByNameAsc(string path, string searchPattern, SearchOption searchOption, int count)
{
    var query = (from f in Directory.GetFiles(path, searchPattern, searchOption)
                 let fi = new FileInfo(f)
                 orderby fi.Name ascending
                 select fi.FullName).Take(count);
    return query.ToArray();
}

SearchOption searchOption解释：

searchOption=0，只在当前目录搜索；

searchOption=1，在搜索操作中包括当前目录和所有子目录。