C++ Program to Find Fibonacci Numbers using Iteration

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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. }

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$ 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)
Press return to continue

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

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn