C++: the program telephone digits outputs only telephone digits that correspond to uppercase letters. rewrite the program so that it processes both uppercase and lowercase letters and outputs the corresponding telephone digit. if the input is something other than an uppercase or lowercase letter, the program must output an appropriate error message.

Following are the program written in the C++ Programming Language:

#include <iostream>  //header file

using namespace std;  //using namespace

int main()  //main function

{

   char letters;

   cout << "To stop the program enter 0" << endl;

   cout << "Enter letter: " ;

   cin >> letters;

   //set while loop

   while (letters != '0' && letters >= 'A' && letters <= 'z') {

       cout << "The letter you entered: " << letters << endl;

       cout << "corresponding telephone digits is: ";

       if (letters > 'Z') {   //if statement

           letters = (int)letters-32; // letters covertion

       }

       switch (letters) { //switch statement

           case'A':

           case'B':

           case'C':

               cout << "2" << "\n""\n"; //print message

               break;  //break the statement

           case'D':

           case'E':

           case'F':

               cout << "3" << "\n""\n";  //print message

               break;  //break the statement

           case'G':

           case'H':

           case'I':

               cout << "4" << "\n""\n";   //print message

               break;  //break the statement

           case'J':

           case'K':

           case'L':

               cout << "5" <<"\n""\n";  //print message

               break; //break the statement

           case'M':

           case'N':

           case'O':

               cout << "6" <<"\n""\n";  //print message

               break; //break the statement

           case'P':

           case'Q':

           case'R':

           case'S':

               cout << "7" << "\n""\n";   //print message

               break;   //break the statement

           case'T':

           case'U':

           case'V':

               cout << "8" << "\n""\n";   //print message

               break;  //break the statement

           case'W':

           case'X':

           case'Y':

           case'Z':

               cout << "9" << "\n""\n";  //print message

               break; //break the statement

           default:

               break; //break the statement

       }

       //print and return letters

       cout << "Enter another letter to find out the number: ";

       cin >> letters;

   }

 return 0;

}

Output:

To stop the program enter 0

Enter letter: a

The letter you entered: a

corresponding telephone digits is: 2

Enter another letter to find out the number: S

The letter you entered: S

corresponding telephone digits is: 7

Enter another letter to find out the number: 0

Explanation:

Here, we define header file "<iostream>" and namespace "std" then, we define main() function.

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