C++ Program for How to check if a given number is Fibonacci number?

// C++ program to check if x is a perfect square
#include <iostream>
#include <math.h>
using namespace std;

// A utility function that returns true if x is perfect square
bool isPerfectSquare(int x)
{
    int s = sqrt(x);
    return (s * s == x);
}

// Returns true if n is a Fibonacci Number, else false
bool isFibonacci(int n)
{
    // n is Fibonacci if one of 5*n*n + 4 or 5*n*n - 4 or both
    // is a perfect square
    return isPerfectSquare(5 * n * n + 4) || isPerfectSquare(5 * n * n - 4);
}

// A utility function to test above functions
int main()
{
    for (int i = 1; i <= 10; i++)
        isFibonacci(i) ? cout << i << " is a Fibonacci Number \n"
                       : cout << i << " is a not Fibonacci Number \n";
    return 0;
}