# C++ Program to Find Fibonacci Numbers using Iteration

This C++ Program demonstrates the the computation of Fibonacci Numbers using Iteration.

Here is source code of the C++ Program to Find Fibonacci Numbers using Iteration. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

1. `/* `
2. ` * C++ Program to Find Fibonacci Numbers using Iteration`
3. ` */`
4. `#include <cstring>`
5. `#include <iostream>`
6. `#include <cstdlib>`
7. `#define ll long long`
8. `using namespace std;`
9. ` `
10. `/* `
11. ` * Iterative function to find Fibonacci Numbers `
12. ` */`
13. `ll fibo_iter(int n)`
14. `{`
15. `    int previous = 1;`
16. `    int current = 1;`
17. `    int next = 1;`
18. `    for (int i = 3; i <= n; ++i) `
19. `    {`
20. `        next = current + previous;`
21. `        previous = current;`
22. `        current = next;`
23. `    }`
24. `    return next;`
25. `}`
26. `/* `
27. ` * Main`
28. ` */`
29. `int main()`
30. `{`
31. `    int n;`
32. `    while (1)`
33. `    {`
34. `        cout<<"Enter the integer n to find nth fibonnaci no.(0 to exit): ";`
35. `        cin>>n;`
36. `        if (n == 0)`
37. `            break;`
38. `        cout<<fibo_iter(n)<<endl;`
39. `    }`
40. `    return 0;`
41. `}`

```\$ g++ fibo_iter.cpp
\$ a.out

Enter the integer n to find nth fibonnaci no.(0 to exit): 1
1
Enter the integer n to find nth fibonnaci no.(0 to exit): 2
1
Enter the integer n to find nth fibonnaci no.(0 to exit): 3
2
Enter the integer n to find nth fibonnaci no.(0 to exit): 4
3
Enter the integer n to find nth fibonnaci no.(0 to exit): 5
5
Enter the integer n to find nth fibonnaci no.(0 to exit): 6
8
Enter the integer n to find nth fibonnaci no.(0 to exit): 7
13
Enter the integer n to find nth fibonnaci no.(0 to exit): 8
21
Enter the integer n to find nth fibonnaci no.(0 to exit): 9
34
Enter the integer n to find nth fibonnaci no.(0 to exit): 10
55
Enter the integer n to find nth fibonnaci no.(0 to exit): 0

------------------
(program exited with code: 1)

Sanfoundry Global Education & Learning Series – 1000 C++ Programs.