C Program for Fibonacci numbers (3 methods)

By | August 24, 2020
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In this article, you will learn to print the Fibonacci sequence of first n term.

Fibonacci Series generates subsequent number by adding two previous numbers.
The first two terms of the Fibonacci sequence are 0 followed by 1.

The Fibonacci sequence: 

0, 1, 1, 2, 3, 5, 8, 13, 21 ...

In mathematical terms, the sequence Fn of Fibonacci numbers is defined by the recurrence relation

Fn = F(n-1) + F(n-2)

where,

F0 = 0 and F1 = 1

Algorithm :

Algorithm of this program is very easy −

  1. Take integer variable A, B, C
  2. Set A = 0, B = 0
  3. DISPLAY A, B
  4. C = A + B
  5. DISPLAY C
  6. Set A = B, B = C
  7. REPEAT from 4 – 6, for n times

Implementation :

1. Using loop :

// C Program for Fibonacci numbers
#include <stdio.h>

// driver code
int main() {
    
    // intial terms
   int a = 0, b = 1;
   // print intial terms
   printf("%d %d ",a, b);
   

   // for next 10 term
   int n = 10;
   
   int i;
   for(i = 1; i <= n-2; i++) {
      
      // to store result
      int c;
      c = a + b;
      
      //print result
      printf("%d ", c);
      
      // new previous two terms
      a = b;
      b = c;
   }
   
   // successful completion
   return 0;
}

Output :

0 1 1 2 3 5 8 13 21 34

2. Using Recursion :

// C Program for Fibonacci numbers
#include<stdio.h>
int fibonacci_series(int);

// driver code
int main()
{
    // take input, i.e., number of terms
   int terms = 10;
   
   int c = 0, i ;
   for ( i = 1 ; i <= terms ; i++ )
   {
       // call fib series function
      printf("%d ", fibonacci_series(c));
      c++; 
   }
 
   return 0;
}

// fib series function
int fibonacci_series(int num)
{
    // for first intial term
   if ( num == 0 ) return 0;
   
   // for second intial term
   else if ( num == 1 ) return 1;
   else
   
   // for more than two terms
   return ( fibonacci_series(num-1) + fibonacci_series(num-2) );
}

Output :

0 1 1 2 3 5 8 13 21 34

3. Using Dynamic Programming :

//Fibonacci Series using Dynamic Programming 
#include<stdio.h> 
  
  // fib function
int fib(int n) 
{ 
  // Declare an array to store Fibonacci numbers 
  int f[n+2];   
  int i; 
  
  // for intial two terms
  f[0] = 0; 
  f[1] = 1; 
  
  // print these intial terms
  printf("%d ", f[0]);
  printf("%d ", f[1]);
  
  // for more two terms
  for (i = 2; i <= n; i++) 
  { 
      // ass previous two numbers and store 
      f[i] = f[i-1] + f[i-2]; 
      printf("%d ", f[i]);
  } 
  
  return f[n]; 
} 
  
int main () 
{ 
    
  // take input, i.e., total number of terms
  int n = 10; 
  

  // call fib function
  fib(n);
  
  // successful completion
  return 0; 
}

Output :

0 1 1 2 3 5 8 13 21 34 55



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