Question

Write a program (attach source file of your program and include its source code your answer script too )

that does the following

• defines a structure for a phonebook contact with at least the following members: contact_name, phone_number, email.
• If the phonebook is empty it will prompt user to create list
• If not empty the program will list all the phonebook contacts and details .

[HINT] Implement a linked list and traverse the linked list                                                     [20]

Answer 1

• I have implemented the above problem using structure in c programming language.

Source code:-

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

//a structure of a single entry in the phonebook defined as a contact
typedef struct {
   //each contact is defined with a name limited to 20 characters
   char name[20];
   //and a telephone number
   //using char because printing of an integer starting with a 0 is not possible
   //treating as a string instead will enable printing
   char telephone[20];
   char email[20];
}Contact;

//a function that prints the information on a contact on position "position"
//takes a pointer to the array of contacts later created in the main
void printContact (Contact *contacts,int position)
{   printf("Name:");
   printf("%s\n",contacts[position].name);
   printf(" Telephone number:");
   printf("%s\n",contacts[position].telephone);
   printf("Email:");
   printf("%s\n",contacts[position].email);
}

//a function that prints out all the contacts in the phonebook
//takes a pointer pointing to the phonebook array and a number showing the number of contacts already entered in the phonebook
void printPhonebook(Contact *contacts,int number)
{
   if(number==0)
   {
       printf("The phone book is empty!");
   }
   else{
       //counter
       int i;
       //starting from 0th index to index number-1 do in a cycle
       for (i=0;i<number;i++)
       {
           //print each contact information...
           //through calling the function printContact and taking i as the wanted position each time
           printf("%d.",i+1);
           printContact(contacts,i);
       }
   }
}

//a function that adds a new contact in the phonebook on index "index" where number is the number of contacts already existing in the phonebook
void addContact(Contact *contacts, int index)
{
   printf("Add a new contact:\n");
   printf("Name:");
   scanf("%s",contacts[index].name);
   printf("Telephone number:");
   scanf("%s",contacts[index].telephone);
   printf("Email Address:");
   scanf("%s",contacts[index].email);
}

int main()
{
printf("************PHONEBOOK************");
//initializing size of counter
size_t contactCounter=0;
//define a counter of type Contact
Contact *contactsPtr;
//allocate memory using calloc
//check difference between calloc and malloc?
contactsPtr=(Contact*)calloc(0,sizeof(Contact));
//define an integer variable select in which the wanted option of the menu is entered by the user
int select;
//do in a cycle while
do{
printf("\nChoose\n"
       "1- ADD A CONTACT\n"
       "2- SHOW THE PHONEBOOK\n"
       "3- EXIT\n");
printf("\nSelect option:");
//store user intput in variable select
scanf("%d",&select);
//clear the input buffer?
getchar();
//set up menu options matching corresponding functions
   switch(select)
   {case 1: //Add a contact
       //increase variable contactCounter as the user chose to add a contact
       contactCounter++;
       //reallocate memory of the contacts ptr by increasing size by 1
       contactsPtr=(Contact*)realloc(contactsPtr, contactCounter*sizeof(Contact));
       //call the function addContact
       addContact(contactsPtr,contactCounter-1);
       break;

   case 2: //Show the phone book
      //calling the function printPhonebook
      printPhonebook(contactsPtr,contactCounter);
      break;
   case 3: //Exit
      break;

   default: printf("You entered an invalid selection. Please try again\n");
       break;
   }
}while(select!=3);
printf("Goodbye!");
//pause the program until user inputs any character
getchar();
//return value
return 0;
}

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Output:-

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