Question

Write this in a C program please.

Structures on Disk The Problem Your task is to write a program that stores and retrieves structures in a file on disk. The file of structures must remain on the disk once your program ends. You should be able to store structures to the file and retrieve from the file after restarting the program. The record that you will be writing to file has the following structure: struct contact {unsigned long phone_number; long first_name_posn; long last_name_posn; long company_name_posn; long email_posn; long next;}; first_name_posn, last_name_posn, company_name_posn, and email_posn are the position in the file of the First Name, Last Name, Company Name, and Email variable strings. These "locations" will be required for writing and reading the information to be stored. When you write the structures on disk you will need to store the First Name, Last Name, Company Name, and Email strings separately from the contact structure. In the file you will write the contact structure first followed by the First Name, Last Name, Company Name, and Email strings (if they exist). The only required information is the Phone Number - all other information is optional. The position "next" stores the location in the file where the next contact record is stored. The file can contain any number of records and associated strings. The name of the file will be myContactList.db and if the file does not exist then you program must create it. Interface (input and output) Your program will have an input interface that does the following: Do you wish to enter a new contact (Yes or No)?: First Name: Last Name: Company Name: Phone Number (enter only numbers): Email:

Answer 1

c++ code for the given problem is as follows:-

#include<iostream>
#include<cstdlib>
#include<cstdio>
using namespace std;
struct contact
{
unsigned long phone_number;
long first_name_posn;
long last_name_posn;
long company_name_posn;
long email_posn;
struct contact *next;
}*head;
class ll
{
public:
ll()
{head=NULL;}
contact* createnode(long phone_number1,long first_name_posn1,
long last_name_posn1,
long company_name_posn1,
long email_posn1);
void last(long phone_number1,long first_name_posn1,
long last_name_posn1,
long company_name_posn1,
long email_posn1);
void display();// Append node (to add new node at last position)
};
contact* ll::createnode(long phone_number1,long first_name_posn1,
long last_name_posn1,
long company_name_posn1,
long email_posn1)
{
struct contact * temp,* ptr;
temp=new(struct contact);
if(temp==NULL)
cout<<"no memory allocated"<<endl;
else
{
temp->phone_number=phone_number1;
temp->first_name_posn=first_name_posn1;
temp->last_name_posn=last_name_posn1;
temp->company_name_posn=first_name_posn1;
temp->email_posn=email_posn1;
temp->next=NULL;
return temp;
}
}
void ll::last(long phone_number1,long first_name_posn1,
long last_name_posn1,
long company_name_posn1,
long email_posn1)
{
struct contact *temp,*p;
temp=createnode(phone_number1,first_name_posn1,last_name_posn1,company_name_posn1,email_posn1);
if (head==NULL)
{
temp->phone_number=phone_number1;
temp->first_name_posn=first_name_posn1;
temp->last_name_posn=last_name_posn1;
temp->company_name_posn=first_name_posn1;
temp->email_posn=email_posn1;
head=temp;
}
else
{
p=head;
while(p->next!=NULL)
{
p=p->next;
}
p->next=temp;
temp->next=NULL;
}
}
void ll::display()
{
struct contact *ptr;
ptr=head;
if(head==NULL)
cout<<"empty"<<endl;
else
{
while(ptr!=NULL)
{
cout<<ptr->phone_number<<" "<<ptr->first_name_posn<<" "<<ptr->last_name_posn<<" "<<ptr->company_name_posn<<" "<<ptr->email_posn<<endl;;
ptr=ptr->next;
}
cout<<" "<<endl;
}
}
int main()
{
   ll l0;
   int k,t=0;
   loop: cout<<"if you wish to enter another contact press 1 "<<endl;
   cin>>k;
   if(k==1)
   {
       long phone_number1;
       long first_name_posn1;
long last_name_posn1;
long company_name_posn1;
long email_posn1;
       cout<<"Enter:"<<endl;
       cout<<"first name:"<<endl;
       cin>>first_name_posn1;
       cout<<"Last name:"<<endl;
       cin>>last_name_posn1;
       cout<<"company name: "<<endl;
       cin>>company_name_posn1;
       cout<<"phone number"<<endl;
       cin>>phone_number1;
       cout<<"email:"<<endl;
       cin>>email_posn1;
      
       l0.last(phone_number1,first_name_posn1,last_name_posn1,company_name_posn1,email_posn1);  
       t++;
       }
       if(t==1)
       {
           goto loop;
           }
       l0.display();
   return 0;
}

note:- in c just use printf and scanf in place of cout and cin and the remaining program remains same and change the header file to #include<stdio.h>

Output:-

CAProgram Files (x86)\Dev-CpplConsolePauser.exe first name 5646 Last name 6465 company name 468 phone number 565 email 5616 if you wish to enter another contact press 1 Enter: first name 6546 Last name 123 company name 65 phone number 26 email: 56 565 5646 6465 5646 5616 26 6546 123 6546 56 Process exited normally. Press any key to continue