Question

#include <iostream>
#include <conio.h>
#include<limits>

using namespace std;

int main(){
char oparand, ch = 'Y';
int num1, num2, result;

while(ch == 'Y'){

cout << "Enter first number: ";
cin >> num1;
while(1){//for handling invalid inputs
if(cin.fail()){
cin.clear();//reseting the buffer
cin.ignore(numeric_limits<streamsize>::max(),'\n');//empty the buffer
cout<<"You have entered wrong input"<<endl;
cout << "Enter first number: ";
cin >> num1;
}
if(!cin.fail())
break;
}

cout << "Enter second number: ";
cin >> num2;
while(1){
if(cin.fail()){
cin.clear();
cin.ignore(numeric_limits<streamsize>::max(),'\n');
cout<<"You have entered wrong input"<<endl;
cout << "Enter second number: ";
cin >> num2;
}
if(!cin.fail())
break;
}

cout<<"a. Add"<<endl;
cout<<"b. Subtract"<<endl;
cout<<"c. Multiply"<<endl;
cout<<"d. Divide"<<endl;
cout << "\nEnter Operand Alphabet: ";
cin >> oparand;
//performing the operation in switch case
switch(oparand)
{
case 'a':
result = num1+num2;
break;

case 'b':
result = num1-num2;
break;

case 'c':
result = num1*num2;
break;

case 'd':
if (num2 == 0) {
cout << "Can not divide by 0!" << endl;
getch();
return 0;
}
result = num1/num2;
break;

default:
cout <<"Invalid Input!";
break;
}

cout << "\nThe result of those numbers is " << result << endl;
cout<<"Want to run again(Y/N)? ";
cin>>ch;
}
getch();
return 0;
}

Question:  When prompting the user for an operation to perform, the program should notify the user if an invalid operation is entered and prompt them for a new one. (Yes. Another loop.)

Answer 1

#include <iostream>
#include <conio.h>
#include<limits>

using namespace std;

int main(){
char oparand, ch = 'Y';
int num1, num2, result;

while(ch == 'Y'){

cout << "Enter first number: ";
cin >> num1;
while(1){//for handling invalid inputs
if(cin.fail()){
cin.clear();//reseting the buffer
cin.ignore(numeric_limits<streamsize>::max(),'\n');//empty the buffer
cout<<"You have entered wrong input"<<endl;
cout << "Enter first number: ";
cin >> num1;
}
if(!cin.fail())
break;
}

cout << "Enter second number: ";
cin >> num2;
while(1){
if(cin.fail()){
cin.clear();
cin.ignore(numeric_limits<streamsize>::max(),'\n');
cout<<"You have entered wrong input"<<endl;
cout << "Enter second number: ";
cin >> num2;
}
if(!cin.fail())
break;
}

oparand = 'x';
while(!(oparand=='a' || oparand=='b'||oparand=='c' || oparand=='d')){
cout<<"a. Add"<<endl;
cout<<"b. Subtract"<<endl;
cout<<"c. Multiply"<<endl;
cout<<"d. Divide"<<endl;
cout << "\nEnter Operand Alphabet: ";
cin >> oparand;
//performing the operation in switch case
switch(oparand)
{
case 'a':
result = num1+num2;
break;

case 'b':
result = num1-num2;
break;

case 'c':
result = num1*num2;
break;

case 'd':
if (num2 == 0) {
cout << "Can not divide by 0!" << endl;
getch();
return 0;
}
result = num1/num2;
break;

default:
cout <<"Invalid Input!"<<endl;
break;
}
}
cout << "\nThe result of those numbers is " << result << endl;
cout<<"Want to run again(Y/N)? ";
cin>>ch;
}
getch();
return 0;
}