visual c++实现内存分配与回收，要求有退出系统，显示分区，分配分区，回收分区功能，给出完整代码

下面是一个简单的 Visual C++ 实现内存分配与回收的示例程序，包括退出系统、显示分区、分配分区和回收分区功能：

#include <iostream>
#include <iomanip>
#include <vector>

using namespace std;

struct MemoryBlock {
    int id;
    int size;
    bool is_free;
};

vector<MemoryBlock> memory;  // 内存块列表

// 初始化内存
void init_memory(int size) {
    memory.clear();
    MemoryBlock block = { 1, size, true };
    memory.push_back(block);
}

// 显示内存分区
void display_memory() {
    cout << "Memory Block List:" << endl;
    cout << setw(5) << "ID" << setw(10) << "Size" << setw(15) << "Status" << endl;
    for (int i = 0; i < memory.size(); i++) {
        MemoryBlock block = memory[i];
        cout << setw(5) << block.id << setw(10) << block.size << setw(15) << (block.is_free ? "Free" : "Used") << endl;
    }
}

// 分配内存
int allocate_memory(int size) {
    for (int i = 0; i < memory.size(); i++) {
        MemoryBlock block = memory[i];
        if (block.is_free && block.size >= size) {
            // 分配内存
            int id = memory.size() + 1;
            MemoryBlock new_block = { id, size, false };
            memory.insert(memory.begin() + i, new_block);
            // 更新剩余内存块
            int remaining_size = block.size - size;
            if (remaining_size > 0) {
                MemoryBlock remaining_block = { id + 1, remaining_size, true };
                memory.insert(memory.begin() + i + 1, remaining_block);
            }
            memory.erase(memory.begin() + i + 1);
            return id;
        }
    }
    return -1;  // 分配失败
}

// 回收内存
bool free_memory(int id) {
    for (int i = 0; i < memory.size(); i++) {
        MemoryBlock block = memory[i];
        if (block.id == id && !block.is_free) {
            // 回收内存
            block.is_free = true;
            memory[i] = block;
            // 合并空闲内存块
            int prev_index = i - 1;
            int next_index = i + 1;
            if (prev_index >= 0 && memory[prev_index].is_free) {
                MemoryBlock prev_block = memory[prev_index];
                prev_block.size += block.size;
                memory[prev_index] = prev_block;
                memory.erase(memory.begin() + i);
                i = prev_index;
            }
            if (next_index < memory.size() && memory[next_index].is_free) {
                MemoryBlock next_block = memory[next_index];
                block.size += next_block.size;
                memory[i] = block;
                memory.erase(memory.begin() + next_index);
            }
            return true;
        }
    }
    return false;  // 回收失败
}

int main() {
    int size;
    cout << "Enter memory size: ";
    cin >> size;
    init_memory(size);
    while (true) {
        display_memory();
        cout << endl;
        cout << "1. Allocate memory" << endl;
        cout << "2. Free memory" << endl;
        cout << "3. Exit system" << endl;
        int choice;
        cout << "Enter your choice: ";
        cin >> choice;
        switch (choice) {
        case 1:
            int alloc_size;
            cout << "Enter allocation size: ";
            cin >> alloc_size;
            int id = allocate_memory(alloc_size);
            if (id == -1) {
                cout << "Failed to allocate memory" << endl;
            } else {
                cout << "Allocated memory ID: " << id << endl;
            }
            break;
        case 2:
            int free_id;
            cout << "Enter memory ID to free: ";
            cin >> free_id;
            if (free_memory(free_id)) {
                cout << "Memory freed successfully" << endl;
            } else {
                cout << "Failed to free memory" << endl;
            }
            break;
        case 3:
            cout << "Exiting system..." << endl;
            return 0;
        default:
            cout << "Invalid choice" << endl;
            break;
        }
    }
    return 0;
}

该程序使用 `vector` 存储内存块列表，实现了初始化内存、显示内存分区、分配内存和回收内存的功能。在分配内存时，程序会查找空闲内存块并分配给用户请求的大小，如果剩余空间不足，则会将剩余部分分割成新的内存块。在回收内存时，程序会查找与用户请求的内存块相邻的空闲内存块并进行合并。