Recursion in C Programming

C programming recursion; In this tutorial, you will learn recursive functions in c programming with the help of definition, syntax, advantages, disadvantages, uses, and examples.

C Recursion

• Recursion Function
• Syntax of Recursive Function
• Flowchart of Recursion
• Advantages and Disadvantages of Recursion
• Example 1 – C Program to Find Factorial of a Number Using Recursive Function
• Example 2 – C program print first n Fibonacci numbers using recursion

Recursive Function

In C programming, a function that calls itself is known as a recursive function. And, this technique is known as recursion.

Syntax of Recursive Function

Syntax of recursive function in c programming; as follows:

returntype recursive_func ([argument list])
{
    statements;
    ... ... ...
    recursive_func ([actual argument]);
    ... ... ...
}

Flowchart of Recursion

Flowchart of recursion function; as follows:

Advantages and Disadvantages of Recursion

Advantages of recursion

• 1. The code may be easier to write.
• 2. To solve such problems which are naturally recursive such as tower of Hanoi.
• 3. Reduce unnecessary calling of function.
• 4. Extremely useful when applying the same solution.
• 5. Recursion reduce the length of code.
• 6. It is very useful in solving the data structure problem.
• 7. Stacks evolutions and infix, prefix, postfix evaluations etc.

Disadvantages of recursion

• 1. Recursive functions are generally slower than non-recursive function.
• 2. It may require a lot of memory space to hold intermediate results on the system stacks.
• 3. Hard to analyze or understand the code.
• 4. It is not more efficient in terms of space and time complexity.
• 5. The computer may run out of memory if the recursive calls are not properly checked.

Example 1 – C Program to Find Factorial of a Number Using Recursive Function

#include<stdio.h>
long int multiplyNumbers(int n);
int main() {
    int n;
    printf("Enter a positive integer: ");
    scanf("%d",&n);
    printf("Factorial of %d = %ld", n, multiplyNumbers(n));
    return 0;
}

long int multiplyNumbers(int n) {
    if (n>=1)
        return n*multiplyNumbers(n-1);
    else
        return 1;
}

Output

Enter a positive integer: 6
Factorial of 6 = 720

Example 2 – C program print first n Fibonacci numbers using recursion

#include<stdio.h>

int fibo(int num)
{
    if(num==1||num==2)
        return 1;
    else
        return (fibo(num-1)+fibo(num-2));  // recursive call
}

int main()
{
    int i,n;
    printf("Enter the required term: ");
    scanf("%d",&n);
    printf("First %d fibonacci numbers aren",n);
    for (i=1; i<=n; i++)
        printf("%dn",fibo(i));
    return 0;
}

Output

Enter the required term: 7
First 7 fibonacci numbers are
1
1
2
3
5
8
13