Step 6: Validate the Contact ID

Easy Section 2: Add Contact Module

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Problem Statement

Extend add_contact() by validating the contact ID after it is read. Keep the Task 5 ID-reading behavior intact. A positive ID is accepted and the program prints Valid ID. A zero or negative ID is rejected and the function returns without continuing to the remaining Add Contact steps. All previously created project code remains intact.

Input Format

A menu choice of 1, followed by one integer contact ID, followed by 0 to exit.

Output Format

Print ID: [id] first. Then print Valid ID for a positive ID or Invalid ID for zero or negative IDs.

Constraints

A valid contact ID must be greater than 0.

Sample Input

1
101
0

Sample Output

Contact Book Ready.
Phonebook Capacity: 100
Contacts: 0
Modules Ready.
Menu:
Add
ID: 101
Valid ID
Menu:
Exit

Explanation

Validating the identifier before accepting the rest of the record prevents invalid records from entering the phonebook. The previously implemented ID input remains unchanged.

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() {
    int id;

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

        // Write your code here
    }
}

void display_contacts() {
}

void search_contact() {
}

void update_contact() {
}

void delete_contact() {
}

int main() {
    int choice;

    printf("Contact Book Ready.");
    printf("\nPhonebook Capacity: %d", sizeof(phonebook)/sizeof(phonebook[0]));
    printf("\nContacts: %d", contact_count);
    printf("\nModules Ready.");

    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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