使用c语言实现lru页面置换算法

好的，下面是使用C语言实现LRU页面置换算法的示例代码：

#include <stdio.h>
#include <stdlib.h>

#define MAXSIZE 5   // 缓存最大大小
#define HIT 1       // 命中
#define MISS 0      // 未命中

// 双向链表节点
typedef struct _node {
    int key;            // 缓存的键
    int value;          // 缓存的值
    struct _node *prev; // 前驱节点指针
    struct _node *next; // 后继节点指针
} Node;

// 双向链表
typedef struct _list {
    int count;          // 缓存的节点数
    Node *head;         // 链表头指针
    Node *tail;         // 链表尾指针
} List;

// 缓存结构体
typedef struct _cache {
    List *list;         // 双向链表指针
    int size;           // 缓存大小
} Cache;

// 创建双向链表
List *createList() {
    List *list = (List *)malloc(sizeof(List));
    list->count = 0;
    list->head = NULL;
    list->tail = NULL;
    return list;
}

// 创建节点
Node *createNode(int key, int value) {
    Node *node = (Node *)malloc(sizeof(Node));
    node->key = key;
    node->value = value;
    node->prev = NULL;
    node->next = NULL;
    return node;
}

// 添加节点到链表头部
void addToHead(List *list, Node *node) {
    if (list->count == 0) {
        list->head = node;
        list->tail = node;
    } else {
        node->next = list->head;
        list->head->prev = node;
        list->head = node;
    }
    list->count++;
}

// 删除节点
void removeNode(List *list, Node *node) {
    if (list->count == 0) {
        return;
    }
    if (list->count == 1) {
        list->head = NULL;
        list->tail = NULL;
    } else if (node == list->head) {
        list->head = node->next;
        list->head->prev = NULL;
    } else if (node == list->tail) {
        list->tail = node->prev;
        list->tail->next = NULL;
    } else {
        node->prev->next = node->next;
        node->next->prev = node->prev;
    }
    free(node);
    list->count--;
}

// 删除链表尾部节点
void removeTail(List *list) {
    if (list->count == 0) {
        return;
    }
    Node *node = list->tail;
    list->tail = node->prev;
    if (list->count == 1) {
        list->head = NULL;
        list->tail = NULL;
    } else {
        list->tail->next = NULL;
    }
    free(node);
    list->count--;
}

// 移动节点到链表头部
void moveToHead(List *list, Node *node) {
    if (node == list->head) {
        return;
    }
    if (node == list->tail) {
        list->tail = node->prev;
        list->tail->next = NULL;
    } else {
        node->prev->next = node->next;
        node->next->prev = node->prev;
    }
    node->prev = NULL;
    node->next = list->head;
    list->head->prev = node;
    list->head = node;
}

// 创建缓存
Cache *createCache(int size) {
    Cache *cache = (Cache *)malloc(sizeof(Cache));
    cache->list = createList();
    cache->size = size;
    return cache;
}

// 获取缓存值
int get(Cache *cache, int key, int *value) {
    Node *node = cache->list->head;
    while (node) {
        if (node->key == key) {
            *value = node->value;
            moveToHead(cache->list, node);
            return HIT;
        }
        node = node->next;
    }
    return MISS;
}

// 设置缓存值
void put(Cache *cache, int key, int value) {
    Node *node = cache->list->head;
    while (node) {
        if (node->key == key) {
            node->value = value;
            moveToHead(cache->list, node);
            return;
        }
        node = node->next;
    }
    node = createNode(key, value);
    addToHead(cache->list, node);
    if (cache->list->count > cache->size) {
        removeTail(cache->list);
    }
}

// 打印缓存
void printCache(Cache *cache) {
    Node *node = cache->list->head;
    while (node) {
        printf("(%d, %d) ", node->key, node->value);
        node = node->next;
    }
    printf("\n");
}

int main() {
    Cache *cache = createCache(MAXSIZE);
    int value;

    put(cache, 1, 1);
    printf("cache: ");
    printCache(cache);

    put(cache, 2, 2);
    printf("cache: ");
    printCache(cache);

    put(cache, 3, 3);
    printf("cache: ");
    printCache(cache);

    get(cache, 1, &value);
    printf("get(1): %d\n", value);
    printf("cache: ");
    printCache(cache);

    put(cache, 4, 4);
    printf("cache: ");
    printCache(cache);

    put(cache, 5, 5);
    printf("cache: ");
    printCache(cache);

    put(cache, 6, 6);
    printf("cache: ");
    printCache(cache);

    get(cache, 3, &value);
    printf("get(3): %d\n", value);
    printf("cache: ");
    printCache(cache);

    return 0;
}

该示例代码实现了一个LRU缓存，支持添加、获取、打印缓存等操作。其中，缓存使用双向链表来实现，每当有新的元素被访问时，将其移动到链表头部，最近最少使用的元素将会被移动到链表尾部，并在缓存达到最大大小时被删除。