c语言通讯录管理系统如何实现菜单交互

Question

即可以根据用户输入的命令，选择不同的操作 。
然后能够保存每次更新的数据。
用线性表实现。

Answer 1

实现菜单交互可以使用循环和条件语句，根据用户输入的命令选择不同的操作。具体步骤如下：

1. 定义一个循环，让程序可以一直运行，直到用户选择退出。
2. 在循环中，输出菜单选项，让用户选择需要执行的操作，可以使用 switch 语句实现不同命令的分支处理。
3. 根据用户选择的命令执行相应的操作，例如添加联系人、删除联系人、修改联系人信息、查找联系人、显示联系人列表等。
4. 对每次更新的数据进行保存，可以将联系人信息保存在文件中，每次程序启动时从文件中加载数据。也可以将联系人信息保存在链表中，每次更新后将链表保存到文件中，程序启动时从文件中加载链表。

以下是一个使用链表实现通讯录管理系统的示例代码，其中包含菜单交互和数据保存功能：

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

#define MAX_NAME_LEN 20
#define MAX_PHONE_LEN 11

// 联系人结构体
typedef struct Contact {
    char name[MAX_NAME_LEN + 1]; // 联系人姓名
    char phone[MAX_PHONE_LEN + 1]; // 联系人电话
    struct Contact *next; // 指向下一个联系人的指针
} Contact;

// 显示菜单
void displayMenu() {
    printf("Welcome to the contact management system.\n");
    printf("1. Add a new contact\n");
    printf("2. Delete a contact\n");
    printf("3. Modify a contact\n");
    printf("4. Search for a contact\n");
    printf("5. Display all contacts\n");
    printf("6. Quit\n");
    printf("Please enter the corresponding number to select an operation: ");
}

// 添加一个联系人
void addContact(Contact **head) {
    Contact *newContact = (Contact*)malloc(sizeof(Contact));
    printf("Please enter the name of the new contact: ");
    scanf("%s", newContact->name);
    printf("Please enter the phone number of the new contact: ");
    scanf("%s", newContact->phone);
    newContact->next = *head;
    *head = newContact;
    printf("The new contact has been added successfully.\n");
}

// 删除一个联系人
void deleteContact(Contact **head) {
    char name[MAX_NAME_LEN + 1];
    printf("Please enter the name of the contact to delete: ");
    scanf("%s", name);
    Contact *prev = NULL;
    Contact *current = *head;
    while (current != NULL) {
        if (strcmp(current->name, name) == 0) {
            if (prev == NULL) {
                *head = current->next;
            } else {
                prev->next = current->next;
            }
            free(current);
            printf("The contact has been deleted successfully.\n");
            return;
        }
        prev = current;
        current = current->next;
    }
    printf("The contact with the name %s does not exist.\n", name);
}

// 修改一个联系人的信息
void modifyContact(Contact *head) {
    char name[MAX_NAME_LEN + 1];
    printf("Please enter the name of the contact to modify: ");
    scanf("%s", name);
    Contact *current = head;
    while (current != NULL) {
        if (strcmp(current->name, name) == 0) {
            printf("Please enter the new phone number of the contact: ");
            scanf("%s", current->phone);
            printf("The contact has been modified successfully.\n");
            return;
        }
        current = current->next;
    }
    printf("The contact with the name %s does not exist.\n", name);
}

// 查找一个联系人
void searchContact(Contact *head) {
    char name[MAX_NAME_LEN + 1];
    printf("Please enter the name of the contact to search: ");
    scanf("%s", name);
    Contact *current = head;
    while (current != NULL) {
        if (strcmp(current->name, name) == 0) {
            printf("Name: %s\n", current->name);
            printf("Phone number: %s\n", current->phone);
            return;
        }
        current = current->next;
    }
    printf("The contact with the name %s does not exist.\n", name);
}

// 显示所有联系人
void displayContacts(Contact *head) {
    if (head == NULL) {
        printf("There are no contacts.\n");
        return;
    }
    printf("The contact list is as follows:\n");
    Contact *current = head;
    while (current != NULL) {
        printf("Name: %s\n", current->name);
        printf("Phone number: %s\n", current->phone);
        current = current->next;
    }
}

// 保存联系人信息到文件
void saveContactsToFile(Contact *head, const char *filename) {
    FILE *file = fopen(filename, "w");
    if (file == NULL) {
        printf("Failed to open file %s.\n", filename);
        return;
    }
    Contact *current = head;
    while (current != NULL) {
        fprintf(file, "%s,%s\n", current->name, current->phone);
        current = current->next;
    }
    fclose(file);
}

// 从文件中加载联系人信息
void loadContactsFromFile(Contact **head, const char *filename) {
    FILE *file = fopen(filename, "r");
    if (file == NULL) {
        printf("Failed to open file %s.\n", filename);
        return;
    }
    char line[MAX_NAME_LEN + MAX_PHONE_LEN + 2];
    while (fgets(line, sizeof(line), file) != NULL) {
        char *name = strtok(line, ",");
        char *phone = strtok(NULL, ",");
        Contact *newContact = (Contact*)malloc(sizeof(Contact));
        strncpy(newContact->name, name, MAX_NAME_LEN);
        strncpy(newContact->phone, phone, MAX_PHONE_LEN);
        newContact->next = *head;
        *head = newContact;
    }
    fclose(file);
}

int main() {
    Contact *head = NULL;
    loadContactsFromFile(&head, "contacts.txt"); // 从文件中加载联系人信息
    int choice;
    do {
        displayMenu(); // 显示菜单
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                addContact(&head); // 添加联系人
                break;
            case 2:
                deleteContact(&head); // 删除联系人
                break;
            case 3:
                modifyContact(head); // 修改联系人信息
                break;
            case 4:
                searchContact(head); // 查找联系人
                break;
            case 5:
                displayContacts(head); // 显示联系人列表
                break;
            case 6:
                saveContactsToFile(head, "contacts.txt"); // 保存联系人信息到文件
                printf("Goodbye!\n");
                break;
            default:
                printf("Invalid choice.\n");
                break;
        }
    } while (choice != 6);
    return 0;
}

在上面的示例代码中，我们使用了链表作为数据结构来存储联系人信息，每次更新联系人信息后将链表保存到文件中，程序启动时从文件中加载链表。同时，我们也实现了菜单交互功能，根据用户输入的命令执行不同的操作。