C Program for Fibonacci Series

A series of numbers in which each number ( Fibonacci number ) is the sum of the two preceding numbers. The simplest is the series  0,1, 1, 2, 3, 5, 8, etc.

• Using For Loop 
• Through Function 
• Through Recursive Function 
• Using Pointer through Recursive Function

1.  Using For Loop:

#include<stdio.h>

main()  {

int i, first = 0, second = 1, sum, limit;

printf  ("Enter The Limit: \n");

scanf  ("%d", &limit);

printf  ("%d %d\n",first, second);

for  (i=1; i <= limit; i++)

 { sum = first + second;

printf ("%d \n",sum);

first = second;

second = sum;

 }   printf("\nThe %dth Fibonacci number is %d",limit, sum); 

}

 Output:

2.  Through Function:

#include<stdio.h>

main()  {

 int n;

 int fib;

 int  fibo (int n);

 printf ("Enter the limit:");

 scanf ("%d",&n);

 fib = fibo(n);

 printf ("\n The %dth Fibonacci number is %ld",n, fib);

}   int  fibo (int n)

{  int first,  second,  sum,  i;

i = 1;

first = 0;

second = 1;

printf ("%d \n%d",first,second);

while(i <= n)   {

sum = first + second;

first = second;

second = sum;

i++;

printf ("\n%d",sum);

}  return sum;   }

Output:

3.  Through Recursive Function:

#include<stdio.h>

main()  {

int n,x,i;

int fib;

int fibo(int);

printf ("Enter the limit:");

scanf ("%d",&n);

n = n + 1;

for(i=0; i <= n;i++)

{   fib = fibo(i);

    printf ("%d \n",fib);   }

printf  ("\n The %dth Fibonacci number is %ld",n-1, fib);

}  int fibo(int x)

{   if (x==0)

 return 0;

 else if (x==1)

 return 1;

 else

 return fibo(x-1) + fibo(x-2);  }

Output:

4.  Using Pointer through Recursive Function:

#include<stdio.h>

main()  {

int fibo(int *a);

int fib,i,n;

printf ("Enetr th limit:");

scanf ("%d",&n);

n = n+ 1;

for(i=0; i <= n; i++)

{    fib = fibo(&i);

printf ("%d\n",fib);

}   printf ("\nThe %dth Fibonacci number is %ld",n-1, fib);

}   int fibo (int *b)

{   int n,f,s;

 f = *b-1;

 s = *b-2;

if(*b==0)

return 0;

else if (*b==1)

return 1;

else

return fibo(&f) + fibo(&s);  }

Output: