C 語言實現雙向鏈表：完整增刪查存代碼

C 語言實現雙向鏈表：完整增刪查存代碼

鏈表節點包含前驅 prior、後繼 next 指針，支持雙向遍歷。本實現涵蓋創建、打印、插入、刪除、查找、文件讀寫持久化。

數據結構定義

#define NULL 0
typedef struct student {
    long num;
    float score;
    struct student *prior;
    struct student *next;
} Student;

Student *head = NULL;

核心操作函數

創建鏈表 (尾插法)

Student *create_linklist() {
    Student *pTail = head, *pTemp;
    int n, i;
    printf("輸入節點數: "); scanf("%d", &n);
    for (i = 0; i < n; i++) {
        pTemp = (Student*)malloc(sizeof(Student));
        printf("輸入學號 成績: "); scanf("%ld %f", &pTemp->num, &pTemp->score);
        pTemp->next = NULL;
        if (head == NULL) {
            head = pTemp;
            pTemp->prior = NULL;
        } else {
            pTail->next = pTemp;
            pTemp->prior = pTail;
        }
        pTail = pTemp;
    }
    return head;
}

打印鏈表

void print_list(Student *p) {
    while (p != NULL) {
        printf("學號:%ld 成績:%.2f\n", p->num, p->score);
        p = p->next;
    }
}

插入節點 (指定位置)

Student *insert_node(Student *head, int pos) {
    Student *q = (Student*)malloc(sizeof(Student));
    printf("輸入學號 成績: "); scanf("%ld %f", &q->num, &q->score);
    Student *p = head;
    int j = 0;
    // 找到插入位置前一個節點
    while (p != NULL && j < pos - 1) { p = p->next; j++; }
    if (p == NULL) { printf("位置非法\n"); free(q); return head; }
    // 插入邏輯
    q->next = p->next;
    q->prior = p;
    if (p->next) p->next->prior = q;
    p->next = q;
    return head;
}

刪除節點 (指定位置)

Student *delete_node(Student *head, int pos) {
    Student *p = head;
    int j = 0;
    while (p != NULL && j < pos) { p = p->next; j++; }
    if (p == NULL) { printf("位置非法\n"); return head; }
    if (p->prior) p->prior->next = p->next;
    else head = p->next; // 刪除頭節點
    if (p->next) p->next->prior = p->prior;
    free(p);
    return head;
}

查找節點 (按學號)

Student *search_node(Student *head, long num) {
    Student *p = head;
    while (p != NULL) {
        if (p->num == num) return p;
        p = p->next;
    }
    return NULL;
}

文件存儲與讀取

void save_to_file(Student *head, char *filename) {
    FILE *fp = fopen(filename, "wb");
    Student *p = head;
    while (p) { fwrite(p, sizeof(Student), 1, fp); p = p->next; }
    fclose(fp);
}

Student *load_from_file(char *filename) {
    FILE *fp = fopen(filename, "rb");
    if (!fp) return NULL;
    Student *p1, *p2;
    head = p1 = (Student*)malloc(sizeof(Student));
    while (fread(p1, sizeof(Student), 1, fp) == 1) {
        p2 = (Student*)malloc(sizeof(Student));
        p1->next = p2;
        p2->prior = p1;
        p1 = p2;
    }
    p1->next = NULL; // 最後多分配一個需處理
    fclose(fp);
    return head;
}

主菜單驅動

void show_menu() {
    printf("\n1.插入 2.刪除 3.查找 4.讀文件 5.存文件 6.打印 7.菜單 0.退出\n");
}

int main() {
    char cmd;
    show_menu();
    while (scanf(" %c", &cmd) == 1) {
        switch (cmd) {
            case '1': insert_node(head, ...); break;
            case '2': delete_node(head, ...); break;
            case '3': search_node(head, ...); break;
            case '4': head = load_from_file("data.dat"); break;
            case '5': save_to_file(head, "data.dat"); break;
            case '6': print_list(head); break;
            case '7': show_menu(); break;
            case '0': return 0;
        }
    }
    return 0;
}

完整代碼可直接編譯運行，實現了雙向鏈表的基本管理功能。