Determining whether a number is a Fibonacci number

Question

I need to to write a Java code that checks whether the user inputed number is in the Fibonacci sequence.

I have no issue writing the Fibonacci sequence to output, b

Answer 1

Thought it was simple until i had to rack my head on it a few minutes. Its quite different from generating a fibonacci sequence. This function returns 1 if is Fibonnaci or 0 if not

public static int isFibonacci (int n){
  int isFib = 0;
  int a = 0, b = 0, c = a + b; // set up the initial values
  do 
   {
    a = b;
    b = c;
    c = a + b;
    if (c == n)
    isFib = 1;
    } while (c<=n && isFin == 0)
  return isFib;
}

public static void main(String [] args){
  System.out.println(isFibonacci(89));
}