写一个通讯录管理系统c语言，能实现数据的修改、插入、删除、保存、排序等。

好的，下面是一个简单的通讯录管理系统的C语言实现，可以实现数据的修改、插入、删除、保存、排序等功能。

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

#define MAX_NAME_LENGTH 20
#define MAX_PHONE_LENGTH 11
#define MAX_CONTACTS 100

struct contact {
    char name[MAX_NAME_LENGTH];
    char phone[MAX_PHONE_LENGTH];
};

int num_contacts = 0;
struct contact contacts[MAX_CONTACTS];

void print_menu() {
    printf("\n\n");
    printf("1. Print contacts\n");
    printf("2. Add contact\n");
    printf("3. Update contact\n");
    printf("4. Delete contact\n");
    printf("5. Save contacts\n");
    printf("6. Load contacts\n");
    printf("7. Sort contacts\n");
    printf("8. Quit\n");
}

void print_contacts() {
    printf("\n\n");
    printf("Contacts:\n");
    for (int i = 0; i < num_contacts; i++) {
        printf("%s, %s\n", contacts[i].name, contacts[i].phone);
    }
}

void add_contact() {
    if (num_contacts == MAX_CONTACTS) {
        printf("\n\n");
        printf("Error: Max contacts reached\n");
        return;
    }

    printf("\n\n");
    printf("Enter name: ");
    scanf("%s", contacts[num_contacts].name);
    printf("Enter phone: ");
    scanf("%s", contacts[num_contacts].phone);

    num_contacts++;

    printf("\n\n");
    printf("Contact added\n");
}

void update_contact() {
    printf("\n\n");
    printf("Enter name to update: ");
    char name[MAX_NAME_LENGTH];
    scanf("%s", name);

    for (int i = 0; i < num_contacts; i++) {
        if (strcmp(contacts[i].name, name) == 0) {
            printf("Enter new phone: ");
            scanf("%s", contacts[i].phone);

            printf("\n\n");
            printf("Contact updated\n");
            return;
        }
    }

    printf("\n\n");
    printf("Error: Contact not found\n");
}

void delete_contact() {
    printf("\n\n");
    printf("Enter name to delete: ");
    char name[MAX_NAME_LENGTH];
    scanf("%s", name);

    for (int i = 0; i < num_contacts; i++) {
        if (strcmp(contacts[i].name, name) == 0) {
            for (int j = i; j < num_contacts - 1; j++) {
                strcpy(contacts[j].name, contacts[j + 1].name);
                strcpy(contacts[j].phone, contacts[j + 1].phone);
            }

            num_contacts--;

            printf("\n\n");
            printf("Contact deleted\n");
            return;
        }
    }

    printf("\n\n");
    printf("Error: Contact not found\n");
}

void save_contacts() {
    FILE* fp;
    fp = fopen("contacts.txt", "w");

    for (int i = 0; i < num_contacts; i++) {
        fprintf(fp, "%s, %s\n", contacts[i].name, contacts[i].phone);
    }

    fclose(fp);

    printf("\n\n");
    printf("Contacts saved\n");
}

void load_contacts() {
    FILE* fp;
    fp = fopen("contacts.txt", "r");

    if (fp == NULL) {
        printf("\n\n");
        printf("Error: Failed to open contacts file\n");
        return;
    }

    char name[MAX_NAME_LENGTH];
    char phone[MAX_PHONE_LENGTH];

    num_contacts = 0;

    while (fscanf(fp, "%[^,], %[^\n]\n", name, phone) != EOF) {
        strcpy(contacts[num_contacts].name, name);
        strcpy(contacts[num_contacts].phone, phone);
        num_contacts++;
    }

    fclose(fp);

    printf("\n\n");
    printf("Contacts loaded\n");
}

void sort_contacts() {
    for (int i = 0; i < num_contacts - 1; i++) {
        for (int j = i + 1; j < num_contacts; j++) {
            if (strcmp(contacts[i].name, contacts[j].name) > 0) {
                struct contact temp = contacts[i];
                contacts[i] = contacts[j];
                contacts[j] = temp;
            }
        }
    }

    printf("\n\n");
    printf("Contacts sorted\n");
}

int main() {
    int choice = 0;

    do {
        print_menu();
        printf("Enter choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                print_contacts();
                break;
            case 2:
                add_contact();
                break;
            case 3:
                update_contact();
                break;
            case 4:
                delete_contact();
                break;
            case 5:
                save_contacts();
                break;
            case 6:
                load_contacts();
                break;
            case 7:
                sort_contacts();
                break;
            case 8:
                printf("\n\n");
                printf("Goodbye!\n");
                break;
            default:
                printf("\n\n");
                printf("Error: Invalid choice\n");
                break;
        }
    } while (choice != 8);

    return 0;
}

这个程序使用一个结构体数组来存储通讯录中的联系人，每个联系人包含一个名字和一个电话号码。程序提供了一个菜单，用户可以选择执行各种操作，例如打印联系人列表，添加联系人，更新联系人信息，删除联系人，保存联系人到文件，从文件中加载联系人，对联系人按照名字排序等。