Count Odd and Even Numbers in a Range from L to R in C++

We are given a range starting from L to R of integer values and the task is to calculate the count of odd numbers and the even numbers in the range.

Input − L = 7, R = 17

Output − Count of Even numbers in a range from L to R are − 5

Count of Odd numbers in a range from L to R are − 6

Input − L = 1, R = 10

Output − Count of Even numbers in a range from L to R are − 5

Count of Odd numbers in a range from L to R are − 5

Approach used in the below program is as follows

• Input the range starting from L to R

• Pass the L and R values to the function to find out the even values and then we will calculate the odd values depending upon the return value.

• Start loop FOR from i to L till R

• Inside the loop, check IF i%2==0 then increment the even count by 1

• Return the even count

• Now to calculate the odd count set odd as (R - L + 1) - even

Example

 Live Demo

#include <iostream>
using namespace std;
int Odd_Even(int L, int R){
   int even = 0;
   for(int i = L ;i < R ;i++){
      if(i%2==0){
         even++;
      }
   }
   return even;
}
int main(){
   int L = 7, R = 17;
   int even = Odd_Even(L, R);
   int odd = (R - L + 1) - even;
   cout<<"Count of Even numbers in a range from L to R are: "<<even<<endl;
   cout<<"Count of Odd numbers in a range from L to R are: "<<odd;
   return 0;
}

Output

If we run the above code it will generate the following output −

Count of Even numbers in a range from L to R are: 5
Count of Odd numbers in a range from L to R are: 6