Question

[C++] Declare three Boolean flags and initialize it as with false value. Ask the user to enter a number, if the number is even make the first flag true, if the number is odd make the second flag true, and if the value entered by the user was not a number make the third flag true. Print out the values of the three flags along with a proper message telling the user about what he/she entered.

Answer 1

Please find the code below:

#include<iostream>                                                                               // including the header file  
using namespace std;

int main()
{
   bool flag1=false,flag2=false,flag3=false;                                                   // declaring and initializing 3 flags to flase
   int number;
  
   cout<<"Please enter a number:";                                                               // Asking user to enter a number and storing the number in number variable
   cin>>number;
  
   if(!cin)                                                                                   // if cin did not received the numeric input
   {
       cin.clear();                                                                           // clear cin
       flag3=true;                                                                               // assign true to flag3
   }
   else
   {
       if(number%2==0)                                                                           // else if the number % 2 is equals to 0
           flag1=true;                                                                           // put true in flag1 because it is an even number
       else
           flag2=true;                                                                           // else put true in flag2 because it is an odd number
   }
  
   cout<<endl<<endl<<"The data in the flags are:";                                               // print the data of the flags
   cout<<endl<<"Flag1 : "<<(flag1?"true":"false");                                               // if the data in flags is 1 print true otherwise false
   cout<<endl<<"Flag2 : "<<(flag2?"true":"false");
   cout<<endl<<"Flag3 : "<<(flag3?"true":"false");
  
   if(flag1==true)                                                                               // print whether the data entered by the user is even, odd or not a number
       cout<<endl<<endl<<"You have entered an even number";
   else if(flag2==true)
       cout<<endl<<"You have entered an odd number";
   else if(flag3==true)
       cout<<endl<<"The data entered by you is not a number";
  
  
}

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Output 1:

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Output 2:

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Output 3:

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Ternary operator:

Please check the following code that we have used in this program:

cout<<endl<<"Flag1 : "<<(flag1?"true":"false");

here (flag1?"true":"false") is the ternary operator

that means check the value in the variable flag1

if the value is true then print true ==> ? re presents true

if the value is false then print false ==> : represents false

we may also write the statement simply as:

cout<<endl<<"Flag1 : "<<flag1;

but c++ represents true as 1 and false as 0, so wherever the value of flag is true it will print 1 and wherever the value of flag is false it will print 0. that is why we have used the ternary operator here.