What is the c plus plus program to print non Fibonacci numbers?

Answer 1

#include<iostream>

#include<iomanip>

#include<math.h> // for floor, log and pow

bool is_fib(unsigned num)

{

// Algorithm: num is Fibonacci if 5*num*num+4 or 5*num*num-4 is a perfect square.

// Note:

// Since 5*num*num could result in a huge number which could easily overflow,

// we'll use a modified algorithm that utilises numbers smaller than num.

double root5 = std::sqrt(5.0);

double phi = (1 + root5) / 2;

long idx = (long)floor( log(num*root5) / log(phi) + 0.5 );

long n = (long)floor( pow(phi, idx)/root5 + 0.5);

return (n == num);

}

int main()

{

// Print non-Fibonacci numbers in range: 0-50

for (unsigned num=0; num<=50; ++num)

if (!is_fib(num))

std::cout

<<std::setw(6)

<<num

<<" is not a Fibonacci number"

<<std::endl;

}