C program to find fibonacci series using only one variable !!!

Problem:
Generating Fibonacci series using only one variable.

There are many ways to achieve this. I have given three ways to do this in the following methods.

Method #1:
We can have a simple function to do this.

Method #2:
The following recursive function would do the job.

Method #3:
The following one works great as well!

Cheers!!
Jack