Question

Write a C program to compute and print Fibonacci values for some integers. You can assume that all input numbers are positive integers.

The Fibonacci numbers are defined as follows:

The first two Fibonacci numbers are 1 and 1. Any Fibonacci number after the first two numbers is the sum of its two predecessors.

The Fibonacci numbers can be listed as the following sequence:

        1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

It is clear that the first two Fibonacci numbers are 1, the third is 2,the fourth is 3, the tenth is 55, and so on.

Here are some sample runs:

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Sample 1:

Enter an integer: 11

The Fibonacci value for 11 is 89

Sample 2:

Enter an integer: 4

The Fibonacci value for 4 is 3

Sample 3:

Enter an integer: 9

The Fibonacci value for 9 is 34

Sample 4:

Enter an integer: 34

The Fibonacci value for 34 is 5702887

Sample 5:

Enter an integer: 1

The Fibonacci value for 1 is 1

Sample 6:

Enter an integer: 20

The Fibonacci value for 20 is 6765

Answer 1

Solution:

#include<stdio.h>
void main()
{
   int first=1,second=1,next,n,temp;
  
   printf("Enter an integer: ");
   scanf("%d",&n);
   temp=n;
   n=n-2;
   next=first;
   while(n>0)
   {
       next=first+second;
       n=n-1;
       first=second;
       second=next;
   }
   printf("The Fibonacci value for %d is %d\n",temp,next);

}

Output: