C Language Tutorial: Implementing Address Book Functionality

Below is the basic process and example code for implementing a simple address book functionality using C language. This address book mainly implements basic functions such as adding contacts, displaying contacts, and searching for contacts.

1. Overall Process

1. 1. Define Data Structure: First, you need to determine the data structure used to store contact information, which generally includes basic information such as name and phone number, typically defined using a structure.

2. 2. Initialize Address Book: Allocate memory space for the address book and set initial properties such as the number of contacts.

3. 3. Function Implementation:

• • Add Contact Function: Receive user input for contact information (such as name and phone), and store it in the address book’s data structure.

• • Display Contacts Function: Traverse the contact data in the address book and output each contact’s information.

• • Search Contact Function: Based on user input for key information (such as name), search for matching contacts in the address book and display their detailed information.

2. Code Example

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

// Define Contact structure
typedef struct Contact {
    char name[20];
    char phone[15];
} Contact;

// Define AddressBook structure
typedef struct AddressBook {
    Contact *contacts;  // Pointer to an array of contacts
    int size;  // Current number of contacts
    int capacity;  // Capacity of the address book
} AddressBook;

// Initialize Address Book
AddressBook initAddressBook(int capacity) {
    AddressBook book;
    book.capacity = capacity;
    book.size = 0;
    book.contacts = (Contact *)malloc(capacity * sizeof(Contact));
    if (book.contacts == NULL) {
        printf("Memory allocation failed!\n");
        exit(1);
    }
    return book;
}

// Add Contact
void addContact(AddressBook *book) {
    if (book->size >= book->capacity) {
        // If the address book is full, consider expanding it; here we simply prompt
        printf("Address book is full, cannot add new contact!\n");
        return;
    }
    Contact newContact;
    printf("Please enter the contact's name:");
    scanf("%s", newContact.name);
    printf("Please enter the contact's phone number:");
    scanf("%s", newContact.phone);
    book->contacts[book->size] = newContact;
    book->size++;
}

// Display All Contacts
void displayContacts(AddressBook book) {
    printf("The contact information in the address book is as follows:\n");
    for (int i = 0; i < book.size; i++) {
        printf("Name: %s, Phone: %s\n", book.contacts[i].name, book.contacts[i].phone);
    }
}

// Search for Contact
void searchContact(AddressBook book) {
    char searchName[20];
    printf("Please enter the name of the contact to search:");
    scanf("%s", searchName);
    for (int i = 0; i < book.size; i++) {
        if (strcmp(book.contacts[i].name, searchName) == 0) {
            printf("Found contact: Name: %s, Phone: %s\n", book.contacts[i].name, book.contacts[i].phone);
            return;
        }
    }
    printf("Contact not found!\n");
}

// Free Address Book Memory
void freeAddressBook(AddressBook book) {
    free(book.contacts);
}

int main() {
    AddressBook myBook = initAddressBook(100);  // Initialize address book with capacity of 100

    int choice;
    do {
        printf("Please select an operation:\n");
        printf("1. Add Contact\n");
        printf("2. Display Contacts\n");
        printf("3. Search Contact\n");
        printf("0. Exit\n");
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                addContact(&myBook);
                break;
            case 2:
                displayContacts(myBook);
                break;
            case 3:
                searchContact(myBook);
                break;
            case 0:
                break;
            default:
                printf("Invalid choice, please try again!\n");
        }
    } while (choice != 0);

    freeAddressBook(myBook);
    return 0;
}

3. Code Explanation

1. 1. Structure Definition Section:

• • First, the Contact structure is defined to store information for a single contact, including two member variables for name and phone number, using character arrays to store the respective string information.

• • Next, the AddressBook structure is defined to represent the entire address book, which contains a pointer contacts to store multiple contact information (by dynamically allocating memory to form an array), as well as a size variable to record the current number of contacts and a capacity variable for the maximum capacity of the address book.

This is just a simple example of an address book. You can further expand the functionality, such as modifying contact information, deleting contacts, sorting contacts by name, etc., and accordingly make further adjustments and improvements to the code structure and functional functions.