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Basic
Switch Case
Goto
Operators
if Statement
Nested if
While Loop
For Loop
Patterns
Array
2D Array
String Function Example
Pointers
Recursion Function
Structure
Excersises
Others



C Program to Find Nth Fibonacci Number using Recursion


Write a C program to Recursion Function to Find nth Fibonacci Number

  • Prompt the user and read the position n for the Fibonacci number.
  • Check for negative input and print an error if invalid.
  • Use a recursion function fibonacci(n) to compute the nth Fibonacci number.
  • Base cases return 0 or 1; recursion case returns sum of previous two Fibonacci numbers.
Example : pgm.c 
#include <stdio.h>

// Recursion function to find nth Fibonacci number
int fibonacci(int n) {
    if (n == 0) return 0;         // Base case 1
    if (n == 1) return 1;         // Base case 2
    return fibonacci(n - 1) + fibonacci(n - 2);  // Recursion call
}

int main() {
    int n;

    printf("Enter the position (n): ");
    scanf("%d", &n);

    if (n < 0)
        printf("Fibonacci is not defined for negative numbers.\n");
    else
        printf("Fibonacci number at position %d is %d\n", n, fibonacci(n));

    return 0;
}

Output :

Enter the position (n): 7
Fibonacci number at position 7 is 13