C++ program to find Fibonacci Series with understanding logic

Fibonacci Series or Sequence

The Fibonacci numbers or Fibonacci series or Fibonacci sequence has first two numbers equal to 1 and 0 and the further each number is consist of the addition of previous two numbers

  1st number = 0
  2nd number = 1
  3rd number = 0+1= 1
  4th number = 1+1= 2
  5th number = 1+2= 3
  And so on.  

 The Fibonacci Sequence can be written as  0,1,1,2,3,5,8,13........


 C++ program to find Fibonacci Series upto given range.This C++ program use simple logic to get the concept of writing code in C++ for Fibonacci Series

1.     #include<iostream>
2.     using namespace std;
3.     int main()
4.     {
5.        int range, first = 0, second = 1, fibonicci=0;
6.        cout << "Enter Range for Terms of Fibonacci Sequence: ";
7.        cin >> range;
8.        cout << "Fibonicci Series upto " << range << " Terms "<< endl;
9.        for ( int c = 0 ; c < range ; c++ )
10.        {
11.           if ( c <= 1 )
12.              fibonicci = c;
13.           else
14.           {
15.              fibonicci = first + second;
16.              first = second;
17.              second = fibonicci;
18.           }
19.           cout << fibonicci <<" ";
20.        }
21.        return 0;
22.     }

  Fibonacci Series program logic explanation

• Before writing C++ code we understand that what is Fibonacci Series and in what sequence numbers are occurs

• After understanding mathematically Fibonacci series completely we thought it in the form of C++ code

• The Fibonacci series is infinite but we can't make a program that display an infinite output

• In above program we take input the range in integer upto which Fibonacci series will be displayed

• For this purpose a for loop has been taken which starts from 0 and terminates less than range for example if Input is 5 then for loop will run from 0 to 4.

• In for loop if  variable 'c' is  less or equal than 1 in this case if statement  will be executed  and if  'c' is greater than 1 else part will be executed for greater than 1

   e.g if range=2 than only
   if part will run.   let input is equal to 5
   Before loop variables values

   first = 0, second = 1, Fibonacci=0;
   After input range=5
   Values are changing in the following sequence

   in below table  ' c '  representing the for loop iterations
   c    first    second   Fibonacci    Output
  
   0     0         1                 0           0 

   1     0         1                 1           0 1
  
   2     0         1           0+1=1         0 1 1
        
          1          1                1           

   3     1         1           1+1=2         0 1 1 2
     
          1         2                  2

   4    1         2             1+2=3         0 1 1 2 3  its final output
   
         2         3                  3      

     
Image View Of  Program (Click on Image To Enlarge)
Fibonacci series in C++ image Code

Fibonacci series C++ Code

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