Question

In C++,

Write a program that retrieves a phone number from a txt files of names and phone numbers. The program should ask the user to enter a name and then print the phone number of that person (or vice versa, number into name) The program should allow the user to repeat the operation as often as they would like to. The data is contained in two text files named "phoneNames.txt" and "phoneNums.txt". The files have one name or one phone number per line. The first phone number in the phone number file corresponds to the first name in the name file. The second phone number in the phone number file corresponds to the second name in the name file. etc. If name or number does not exist, display error and let user try again.

Example:

Welcome to the Phone Number Lookup Program!

Enter the phone number you wish to look up: 510-649-0730

That phone number belongs to Pamela Contag

Would you like to find another name? (Y or N): y

Enter the phone number you wish to look up: 614-685-5195

That phone number belongs to Tom Daly

Would you like to find another name? (Y or N): y

Enter the phone number you wish to look up: 256-512-1024

256-512-1024 is not in the data base, sorry.

Would you like to find another name? (Y or N): n

End program.

In depth Comments in code would be greatly appreciated to help follow along

Answer 1

I hope this is what you want. if you still have any doubt please let me know. comment is done where it is necessary. I have implemented both the method based on number as well as name (name is actually).

Transform function convert both string into lower case

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#include <iostream> // Header file for input and output
#include <fstream> // header file for file operation
#include<string.h> //header file for string function
#include<algorithm>
using namespace std;
int main()
{

    ifstream fin,fin1; // input file stream for reading purpose two object fin, fin1
    string line,line1,line2; //line for phone number, line1 for name, line2 for inputby user

    char ch='y';//for reapeting operation
    int t; //for selecting case
   cout<<"Welcome to the phone number look up program"<<endl;

    while(ch=='y'||ch=='Y'){ //loop untill y is pressed
       cout<<"Enter a number 1. for searching name from number and 2. for searching number for name="<<endl;
       cin>>t; //input from user is read into t which select a case
       cin.ignore(); // ignoring first enter
    
       int x=0; // for compare function
       int flag1=0,flag=0;// for printing validation
       switch(t){
           case 1 :     fin.open("phoneNames.txt", ios::out | ios::in); //opening file phonenames
    fin1.open("phoneNumber.txt", ios::out | ios::in);//openaning file phonenumber
         
                       flag=0;
                       cout<<"Enter the Number you wish to lookup= ";
                       getline(cin,line2); // reading all string in line 2
                
                         while (fin) { // untill file is end
                            getline(fin, line);// reading a line from file phonename
                           getline(fin1,line1); // reading a line from file phone number
                           if((x=line1.compare(line2))==0){ // comparing phone number with input if it is 0 it is match
                               cout<<"That Number belongs to"<<line<<endl;// printing name
                               flag=1;// for printing when mtch is foun we are setting flag to 1
                               break;
                           }
                        }
                   
                        if(flag==0){ // if flag==0 than match not found
                                cout<<line2<<" is not in database sorry!"<<endl;
                       }
                       fin.close(); //file close
                         fin1.close();
                        break;
        
           case 2:
                      fin.open("phoneNames.txt", ios::out | ios::in); //opening file phonenames
    fin1.open("phoneNumber.txt", ios::out | ios::in);//openaning file phonenumber
                   
                         flag1=0;
                       cout<<"Enter the Name you wish to lookup= ";
                        
                       getline(cin,line2); // reading all string in line 2
                         
                        while (fin1) { //untill file is end
                            getline(fin, line);
                           getline(fin1,line1);
                           transform(line2.begin(),line2.end(),line2.begin(),::tolower);
                           transform(line.begin(),line.end(),line.begin(),::tolower);
                         
                           if((x=line.compare(line2))==0){
                               cout<<"That number of "<<line2 <<"is "<<line1<<endl;
                               flag1=1;
                               break;
                           }
                        }
                      
                        if(flag1==0){
                                cout<<line2<<" is not in database sorry!"<<endl;
                                   fin1.seekg(0, ios::beg);
                              
                       }
                        fin.close(); //file close
                         fin1.close();
                       break;
     
        default: cout<<"Enter valid choice"<<endl;
        
       }

       cout<<"Would you like another Name OR Number to continue press y ";
       cin>>ch;
   }

    return 0;
}

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Classes Debug Untitied 60 O C:\Users\Makadia Vyomesh\Documents\Untitled1.exe 61 E if((x=line.compare(line2))==0){ cout<<"That number of "<<line2 Enter a number 1. for searching name from number and 2. for searching number for name= flag1=1; break; Welcome to the phone number look up program 62 63 2 64 Enter the Name you wish to lookup= John Doe 65 That number of John Doeis 440-879-9876 Would you like another Name OR Number to continue press y y Enter a number 1. for searching name from number and 2. for searching number for name= 66 67 68 É if(flag1==0){ Enter the Name you wish to lookup= John John is not in database sorry! fin1.seekg(0, ios::beg); Would you like another Name OR Number to continue press y y cout<<line2<<" is not in datab 69 70 71 Enter a number 1. for searching name from number and 2. for searching number for name= 72 73 fin.close(); //file close fin1.close(); break; Enter the Number you wish to lookup= 440-879-9876 That Number belongs toJohn Doe Would you like another Name OR Number to continue press y n 74 75 76 default: cout<<"Enter valid choice"<<endl; 77 Process exited after 34.72 seconds with return value 0 78 Press any key to continue . 79 80 cout<<"Would you like another Name OR Number to continu cin>>ch; 81 82 83 84 85 86 return 0; 87 88 38 Compiler Resources dlh Compile Log Debug 3 Find Results Close Compilation results... Abort Compilation Errors: 0 Warnings: 0 Output Filename: C:\Users\Makadia Vyomesh\Documents\Untitledl.exe Shorten compiler paths Output Size: 1.83431243896484 MiB Compilation Time: 1.16s Col: ne: 88 Sel: 3906 Lines: 88 Length: 3908 Insert Done parsing in 0 seconds

Classes Debug Untitied 60 O C:\Users\Makadia Vyomesh\Documents\Untitled1.exe 61 E if((x=line.compare(line2))==0){ cout<<"That number of "<<line2 Enter a number 1. for searching name from number and 2. for searching number for name= flag1=1; break; Welcome to the phone number look up program 62 63 2 64 Enter the Name you wish to lookup= John Doe 65 That number of John Doeis 440-879-9876 Would you like another Name OR Number to continue press y y Enter a number 1. for searching name from number and 2. for searching number for name= 66 67 68 É if(flag1==0){ Enter the Name you wish to lookup= John John is not in database sorry! fin1.seekg(0, ios::beg); Would you like another Name OR Number to continue press y y cout<<line2<<" is not in datab 69 70 71 Enter a number 1. for searching name from number and 2. for searching number for name= 72 73 fin.close(); //file close fin1.close(); break; Enter the Number you wish to lookup= 440-879-9876 That Number belongs toJohn Doe Would you like another Name OR Number to continue press y n 74 75 76 default: cout<<"Enter valid choice"<<endl; 77 Process exited after 34.72 seconds with return value 0 78 Press any key to continue . 79 80 cout<<"Would you like another Name OR Number to continu cin>>ch; 81 82 83 84 85 86 return 0; 87 88 38 Compiler Resources dlh Compile Log Debug 3 Find Results Close Compilation results... Abort Compilation Errors: 0 Warnings: 0 Output Filename: C:\Users\Makadia Vyomesh\Documents\Untitledl.exe Shorten compiler paths Output Size: 1.83431243896484 MiB Compilation Time: 1.16s Col: ne: 88 Sel: 3906 Lines: 88 Length: 3908 Insert Done parsing in 0 seconds