用C++编写一程序，模拟一个简单的文件管理系统。树型结构，目录下可以是目录，也可以是文件。 在此文件管理系统，可实现的操作有： 改变目录(可以回到根目录）：格式：cd <目录名> 显示目录：格式：dir<目录名> 创建目录：格式：md <目录名> 删除目录：格式：rd<目录名> 新建文件：格式：edit<文件名> 删除文件：格式：del<文件名> 退出文件系统：exit

以下是一个简单的文件管理系统的实现，使用了C++的面向对象编程思想，采用树型结构存储目录与文件信息：

#include <iostream>
#include <string>
#include <vector>
using namespace std;

class Node {
public:
    string name;
    bool isFile;
    vector<Node*> children;
    Node(string n, bool f) {
        name = n;
        isFile = f;
    }
};

class FileSystem {
private:
    Node* root;
    Node* current;
public:
    FileSystem() {
        root = new Node("", false);
        current = root;
    }
    void run() {
        cout << "Simple File System\n";
        string command;
        while (true) {
            cout << ">>";
            cin >> command;
            if (command == "cd") {
                string name;
                cin >> name;
                changeDirectory(name);
            }
            else if (command == "dir") {
                string name;
                cin >> name;
                displayDirectory(name);
            }
            else if (command == "md") {
                string name;
                cin >> name;
                createDirectory(name);
            }
            else if (command == "rd") {
                string name;
                cin >> name;
                deleteDirectory(name);
            }
            else if (command == "edit") {
                string name;
                cin >> name;
                createFile(name);
            }
            else if (command == "del") {
                string name;
                cin >> name;
                deleteFile(name);
            }
            else if (command == "exit") {
                exit(0);
            }
            else {
                cout << "Invalid command.\n";
            }
        }
    }
    void changeDirectory(string name) {
        if (name == "") {
            current = root;
            return;
        }
        for (Node* child : current->children) {
            if (child->name == name && !child->isFile) {
                current = child;
                return;
            }
        }
        cout << "Directory not found.\n";
    }
    void displayDirectory(string name) {
        if (name == "") {
            name = current->name;
        }
        for (Node* child : current->children) {
            if (child->name == name) {
                if (!child->isFile) {
                    cout << "Directory: " << child->name << "\n";
                    for (Node* subchild : child->children) {
                        if (subchild->isFile) {
                            cout << "File: " << subchild->name << "\n";
                        }
                        else {
                            cout << "Directory: " << subchild->name << "\n";
                        }
                    }
                }
                else {
                    cout << "File: " << child->name << "\n";
                }
                return;
            }
        }
        cout << "Directory not found.\n";
    }
    void createDirectory(string name) {
        for (Node* child : current->children) {
            if (child->name == name && !child->isFile) {
                cout << "Directory already exists.\n";
                return;
            }
        }
        Node* newDirectory = new Node(name, false);
        current->children.push_back(newDirectory);
    }
    void deleteDirectory(string name) {
        for (int i = 0; i < current->children.size(); i++) {
            Node* child = current->children[i];
            if (child->name == name && !child->isFile) {
                current->children.erase(current->children.begin() + i);
                delete child;
                return;
            }
        }
        cout << "Directory not found.\n";
    }
    void createFile(string name) {
        for (Node* child : current->children) {
            if (child->name == name && child->isFile) {
                cout << "File already exists.\n";
                return;
            }
        }
        Node* newFile = new Node(name, true);
        current->children.push_back(newFile);
    }
    void deleteFile(string name) {
        for (int i = 0; i < current->children.size(); i++) {
            Node* child = current->children[i];
            if (child->name == name && child->isFile) {
                current->children.erase(current->children.begin() + i);
                delete child;
                return;
            }
        }
        cout << "File not found.\n";
    }
};

int main() {
    FileSystem fs;
    fs.run();
    return 0;
}

该程序实现了用户可以进入不同目录、创建、显示和删除目录与文件等基本功能，用户可以通过输入不同的命令来操作文件系统。