A contact management system is a program that enables users to easily store and find contact information, such as names, addresses, telephone numbers and email address. This  contact management system can be used to add, view, edit, search and delete contacts. All added and edited records are saved in a file.

Code:

#include<fstream>
#include<conio.h>
#include<string.h>
#include<iomanip>
#include<iostream>

using namespace std;

class contact
{
	long ph;
    char name[20],add[20],email[30];
	
	public:
 
	void create_contact()
	{
            cout<<"Phone: ";
            cin>>ph;
            
            cout<<"Name: ";
            cin.ignore();
            cin>>name;
            
			cout<<"Address: ";
            cin.ignore();
            cin>>add;

            cout<<"Email address: ";
            cin.ignore();
            cin>>email;

            cout<<"\n";
	}
	
	void show_contact()
	{
		cout<<endl<<"Phone #: "<<ph;
		cout<<endl<<"Name: "<<name;
		cout<<endl<<"Address: "<<add;
		cout<<endl<<"Email Address : "<<email;
	}
	
	long getPhone()
	{
		return ph;
	}
	
	char* getName()
	{
		return name;
	}
	
	char* getAddress()
	{
		return add;
	}
	
	char* getEmail()
	{
		return email;
	}
}; 
 

fstream fp;
contact cont;
 
void save_contact()
{
	fp.open("contactBook.dat",ios::out|ios::app);
	cont.create_contact();
	fp.write((char*)&cont,sizeof(contact));
	fp.close();
	cout<<endl<<endl<<"Contact Has Been Sucessfully Created...";
	getchar();
}

void show_all_contacts()
{
	system("cls");
	 cout<<"\n\t\t================================\n\t\t\tLIST OF CONTACTS\n\t\t================================\n";
	fp.open("contactBook.dat",ios::in);
	while(fp.read((char*)&cont,sizeof(contact)))
	{
		cont.show_contact();
		cout<<endl<<"=================================================\n"<<endl;
	}
	fp.close();
}
 
 
void display_contact(int num)
{
	bool found;
	int ch;

		 found=false;
	fp.open("contactBook.dat",ios::in);
	while(fp.read((char*)&cont,sizeof(contact)))
	{
		if(cont.getPhone()==num)
		{
			system("cls");
			cont.show_contact();
			found=true;
		}
	}
	
	fp.close();
	if(found == false){
	cout<<"\n\nNo record found...";}
	
	    
	getchar();
}


void edit_contact()
{
	int num;
	bool found=false;
	system("cls");
	cout<<"..::Edit contact\n===============================\n\n\t..::Enter the number of contact to edit:";
    cin>>num;
	
	fp.open("contactBook.dat",ios::in|ios::out);
	while(fp.read((char*)&cont,sizeof(contact)) && found==false)
	{
		if(cont.getPhone()==num)
		{
			cont.show_contact();
            cout<<"\nPlease Enter The New Details of Contact: "<<endl;
			cont.create_contact();
			int pos=-1*sizeof(cont);
			fp.seekp(pos,ios::cur);
			fp.write((char*)&cont,sizeof(cont));
			cout<<endl<<endl<<"\t Contact Successfully Updated...";
			found=true;
		}
	}
	fp.close();
	if(found==false)
		cout<<endl<<endl<<"Contact Not Found...";


}


void delete_contact()
{
	int num;
	system("cls");
	cout<<endl<<endl<<"Please Enter The contact #: ";
	cin>>num;
	fp.open("contactBook.dat",ios::in|ios::out);
	fstream fp2;
	fp2.open("Temp.dat",ios::out);
	fp.seekg(0,ios::beg);
	while(fp.read((char*)&cont,sizeof(contact)))
	{
		if(cont.getPhone()!=num)
		{
			fp2.write((char*)&cont,sizeof(contact));
		}
	}
	fp2.close();
	fp.close();
	remove("contactBook.dat");
	rename("Temp.dat","contactBook.dat");
	cout<<endl<<endl<<"\tContact Deleted...";
}


int main(int argc, char *argv[])
{
		system("cls");
	system("color 03");
  	cout<<"\t\t\t\t*\t*";
  	cout<<"\t\t\t\t**\t**";
   	cout<<"\t\t\t\t***\t***";
   	cout<<"\t\t\t\t****\t****";
   	cout<<"\t\t\t\t*****\t*****";
    cout<<"\t\t\t\t******\t******";
   	cout<<"\t\t\t\t*******\t*******";
   	cout<<"\t\t\t\t*******\t*******";
   	cout<<"\t\t\t\t******\t******";
   	cout<<"\t\t\t\t*****\t*****";
   	cout<<"\t\t\t\t****\t****";
   	cout<<"\t\t\t\t***\t***";
   	cout<<"\t\t\t\t**\t**";
   	cout<<"\t\t\t\t*\t*";
	
    for(;;)
    {
		    int ch;
    cout<<"\n\t **** Welcome to Contact Management System ****";
    cout<<"\n\n\n\t\t\tMAIN MENU\n\t\t=====================\n\t\t[1] Add a new Contact\n\t\t[2] List all Contacts\n\t\t[3] Search for contact\n\t\t[4] Edit a Contact\n\t\t[5] Delete a Contact\n\t\t[0] Exit\n\t\t=================\n\t\t";
    cout<<"Enter the choice:";

    cin>>ch;

    switch(ch)
    {
    	case 0: cout<<"\n\n\t\tThank you for using CMS...";
    		exit(0);
    			break;
        break;
    	     break;
    	case 1:save_contact();
    		break;
    	case 2:show_all_contacts();
    		break;
   		case 3:
		    int num;
            system("cls");
            cout<<"\n\n\tPhone: ";
            cin>>num;
			display_contact(num);
    		break;
    	case 4:edit_contact();
    		break;
    	case 5:delete_contact();
    		break;
    	default:
    		break;
    }
    
    
    

	int opt;
   cout<<"\n\n\n..::Enter the Choice:\n\n\t[1] Main Menu\t\t[0] Exit\n";

   cin>>opt;

    switch (opt)

    {

    case 1:
		system("cls");
        continue;

    case 0:

       exit(0);

}
	}
	return 0;
}