print fibo big numbers in c++ or c language

Question

I write this code for show fibonacci series using recursion.But It not show correctly for n>43 (ex: for n=100 show:-980107325).

#include
#inc         


        

Answer 1

Keep in mind that the n-th fibonacci number is (approximately) ((1 + sqrt(5))/2)^n.

This allows you to get the value for n that allows the result to fit in 32 /64 unsigned integers. For signed remember that you lose one bit.