首次适应算法C++简单实现

首次适应算法是一种内存分配算法，其核心思想是将空闲内存分区组织成一个链表，每次请求内存时，从链表的头部开始查找第一个满足要求的空闲分区。这里提供一个用C++实现首次适应算法的简单程序，代码如下所示：

#include <iostream>
using namespace std;

struct block {
    int size;
    int start_address;
    struct block *next;
};

struct block *start = NULL;

void allocate_memory(int size) {
    struct block *newblock, *current;
    newblock = new struct block;
    newblock->size = size;
    if (start == NULL) {
        newblock->start_address = 0;
        start = newblock;
        start->next = NULL;
    } else {
        current = start;
        while (current->next != NULL) {
            current = current->next;
        }
        newblock->start_address = current->start_address + current->size;
        current->next = newblock;
        newblock->next = NULL;
    }
    cout << "Memory allocated successfully from " << newblock->start_address << " to " << newblock->start_address + newblock->size - 1 << endl;
}

void deallocate_memory(int start_address) {
    struct block *current, *previous;
    current = start;
    while (current != NULL) {
        if (current->start_address == start_address) {
            if (current == start) {
                start = current->next;
            } else {
                previous->next = current->next;
            }
            delete(current);
            cout << "Memory block starting from " << start_address << " has been deallocated successfully" << endl;
            return;
        }
        previous = current;
        current = current->next;
    }
    cout << "Memory block starting from " << start_address << " not found" << endl;
}

int main() {
    allocate_memory(100);
    allocate_memory(200);
    deallocate_memory(0);
    allocate_memory(50);
    return 0;
}

在这个程序中，`struct block`定义了一个内存块的数据结构，包括大小、起始地址以及指向下一个内存块的指针。`allocate_memory`函数用于分配内存，它创建一个新的内存块，并将其连接到链表的尾部。`deallocate_memory`函数用于释放内存，它搜索链表以找到与给定起始地址相匹配的内存块，并将其从链表中删除。在`main`函数中，我们演示了如何使用这些函数来分配和释放内存。