In this tutorial, we will write a C++ program to check for sunny numbers.

## What is Sunny Number?

A number ** N** is said to be a

**sunny number**if the number next to the given number

**is a perfect square.**

` (N+1)`

**Example:** Let us take a Number **8**, then the next number is ** 8+1=9** and as

**3**is a square root of

**9**, hence

**8**is a sunny Number.

Another example, let the number be **5**, then ** 5+1=6**, that has no square roots, hence

**5**is not a sunny Number.

**Sunny Number Program in C++**

**Question**: Check if the given number is a sunny number or not in C++ programming.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | #include <iostream> #include <cmath> using namespace std; bool is_sunny(int); //function prototype int main() { int num; cout << "Enter the number: "; cin >> num; if (is_sunny(num)) cout << num << " is a sunny number"; else cout << num << " is NOT a sunny number"; return 0; } bool is_sunny(int n) { // find the square root int square = sqrt(n + 1); return (square *square == n); } |

**Output:**

`Enter the number: 81`

81 is a sunny number