写个通讯录系统的c语言代码，包括增加、删除、修改、查找、保存的功能

下面是一个简单的通讯录系统的C语言代码，包括增加、删除、修改、查找、保存的功能。该系统使用了结构体和文件读写操作：

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

#define MAX_NAME_LEN 20
#define MAX_PHONE_LEN 11
#define MAX_EMAIL_LEN 30

typedef struct {
    char name[MAX_NAME_LEN];
    char phone[MAX_PHONE_LEN];
    char email[MAX_EMAIL_LEN];
} Contact;

void add_contact(Contact *contacts, int *count);
void delete_contact(Contact *contacts, int *count);
void modify_contact(Contact *contacts, int count);
void search_contact(Contact *contacts, int count);
void save_contacts(Contact *contacts, int count);

int main() {
    Contact contacts[100];
    int count = 0;
    int choice;

    while (1) {
        printf("1. Add Contact\n");
        printf("2. Delete Contact\n");
        printf("3. Modify Contact\n");
        printf("4. Search Contact\n");
        printf("5. Save Contacts\n");
        printf("6. Quit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                add_contact(&contacts[count], &count);
                break;
            case 2:
                delete_contact(contacts, &count);
                break;
            case 3:
                modify_contact(contacts, count);
                break;
            case 4:
                search_contact(contacts, count);
                break;
            case 5:
                save_contacts(contacts, count);
                break;
            case 6:
                exit(0);
            default:
                printf("Invalid choice!\n");
        }
    }

    return 0;
}

void add_contact(Contact *contacts, int *count) {
    printf("Enter name: ");
    scanf("%s", contacts->name);
    printf("Enter phone: ");
    scanf("%s", contacts->phone);
    printf("Enter email: ");
    scanf("%s", contacts->email);
    (*count)++;
}

void delete_contact(Contact *contacts, int *count) {
    char name[MAX_NAME_LEN];
    int i, j, found = 0;

    printf("Enter name to delete: ");
    scanf("%s", name);

    for (i = 0; i < *count; i++) {
        if (strcmp(contacts[i].name, name) == 0) {
            found = 1;
            for (j = i; j < *count - 1; j++) {
                contacts[j] = contacts[j + 1];
            }
            (*count)--;
            break;
        }
    }

    if (found) {
        printf("Contact deleted successfully!\n");
    } else {
        printf("Contact not found!\n");
    }
}

void modify_contact(Contact *contacts, int count) {
    char name[MAX_NAME_LEN];
    int i, found = 0;

    printf("Enter name to modify: ");
    scanf("%s", name);

    for (i = 0; i < count; i++) {
        if (strcmp(contacts[i].name, name) == 0) {
            found = 1;
            printf("Enter new phone: ");
            scanf("%s", contacts[i].phone);
            printf("Enter new email: ");
            scanf("%s", contacts[i].email);
            break;
        }
    }

    if (found) {
        printf("Contact modified successfully!\n");
    } else {
        printf("Contact not found!\n");
    }
}

void search_contact(Contact *contacts, int count) {
    char name[MAX_NAME_LEN];
    int i, found = 0;

    printf("Enter name to search: ");
    scanf("%s", name);

    for (i = 0; i < count; i++) {
        if (strcmp(contacts[i].name, name) == 0) {
            found = 1;
            printf("Name: %s\nPhone: %s\nEmail: %s\n",
                   contacts[i].name, contacts[i].phone, contacts[i].email);
            break;
        }
    }

    if (!found) {
        printf("Contact not found!\n");
    }
}

void save_contacts(Contact *contacts, int count) {
    FILE *file = fopen("contacts.txt", "w");
    int i;

    if (file == NULL) {
        printf("Failed to open file!\n");
        return;
    }

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

    fclose(file);
    printf("Contacts saved successfully!\n");
}

在该代码中，`Contact` 结构体表示每个通讯录条目，包括姓名、电话和电子邮件地址。`add_contact` 函数用于添加新条目，`delete_contact` 函数用于删除条目，`modify_contact` 函数用于修改条目，`search_contact` 函数用于搜索条目，`save_contacts` 函数用于将条目保存到文件中。在 `main` 函数中，使用一个无限循环来提供菜单选项。