Step 12: Handle an Empty Phonebook

Easy Section 3: Display Module

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Problem Statement

Implement the first part of the display_contacts() function. When the phonebook contains no contacts, print Phonebook Empty and return without attempting to display a table. Retain the complete Task 11 program and all previously implemented Add Contact functionality. The display function is the only new coding area in this task.

Input Format

A sequence of menu choices ending with 0. The Display option is represented by 2.

Output Format

When Display is selected while contact_count is 0, print Phonebook Empty.

Constraints

When contact_count is 0, display_contacts() must return immediately after printing the empty-state message.

Sample Input

2
0

Sample Output

Contact Book Ready.
Phonebook Capacity: 100
Contacts: 0
Menu:
Display
Phonebook Empty
Menu:
Exit

Explanation

A display module should handle the empty state before trying to render contact records. This prevents confusing blank output and establishes a permanent early-return condition for the display function.

Starter Code

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

struct Contact {
    int id;
    char name[50];
    char phone[15];
};

struct Contact phonebook[100];
int contact_count = 0;

void add_contact();
void display_contacts();
void search_contact();
void update_contact();
void delete_contact();

void add_contact() {
    if (contact_count >= 100) {
        printf("\nPhonebook Full");
        return;
    }

    int id;

    if (scanf("%d", &id) == 1) {
        printf("\nID: %d", id);

        if (id > 0) {
            printf("\nValid ID");

            {
                int duplicate = 0;

                for (int i = 0; i < contact_count; i++) {
                    if (phonebook[i].id == id) {
                        duplicate = 1;
                        break;
                    }
                }

                if (duplicate) {
                    printf("\nDuplicate ID");
                    return;
                }
            }

            getchar();

            if (fgets(phonebook[contact_count].name,
                      sizeof(phonebook[contact_count].name), stdin) != NULL) {
                phonebook[contact_count].name[
                    strcspn(phonebook[contact_count].name, "\n")
                ] = '\0';

                printf("\nName: %s", phonebook[contact_count].name);

                {
                    char phone_input[100];

                    if (fgets(phone_input, sizeof(phone_input), stdin) != NULL) {
                        phone_input[
                            strcspn(phone_input, "\n")
                        ] = '\0';

                        printf("\nPhone: %s", phone_input);

                        if (strlen(phone_input) >= 1 &&
                            strlen(phone_input) <= 14) {
                            strcpy(phonebook[contact_count].phone, phone_input);
                            printf("\nValid Phone");

                            phonebook[contact_count].id = id;
                            contact_count++;

                            printf("\nContact Added");
                        } else {
                            printf("\nInvalid Phone");
                        }
                    }
                }
            }
        } else {
            printf("\nInvalid ID");
        }
    }
}

void display_contacts() {
    // Write your code here
}

void search_contact() {
}

void update_contact() {
}

void delete_contact() {
}

int main() {
    int choice;

    printf("Contact Book Ready.");
    printf("\nPhonebook Capacity: %d", 100);
    printf("\nContacts: %d", contact_count);

    while (1) {
        printf("\nMenu:");

        if (scanf("%d", &choice) != 1) {
            break;
        }

        switch (choice) {
            case 1:
                printf("\nAdd");
                add_contact();
                break;

            case 2:
                printf("\nDisplay");
                display_contacts();
                break;

            case 3:
                printf("\nSearch");
                search_contact();
                break;

            case 4:
                printf("\nUpdate");
                update_contact();
                break;

            case 5:
                printf("\nDelete");
                delete_contact();
                break;

            case 0:
                printf("\nExit");
                return 0;

            default:
                printf("\nInvalid Choice");
                break;
        }
    }

    return 0;
}

Limits

Time Limit: 1s
Memory Limit: 256MB

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