Recursively retrieve all files and folders under the specified drive letter, recursively retrieve the specified drive letter

Recursively retrieve all files and folders under the specified drive letter, recursively retrieve the specified drive letter
/// <Summary>
/// Recursively retrieve all files and folders under the specified drive letter
/// Some folder Access Permissions
/// </Summary>
/// <Param name = "path"> string path = @ "G: \"; </param>
/// <Param name = "filter"> string filter = "*. mp3"; </param> Recursion (recursion): Programming skills for programs to call themselves.

Recursion meets two conditions:

1) there is a process of repeated execution (calling itself)

2) Conditions for jumping out of the repeated execution process (recursive Exit)