Python: Recursion (Recursive Function)

In Python, Recursion is the process of defining something in terms of itself. It is a common mathematical and programming concept. It is the process in which a function can directly or indirectly call itself.

Advantages of using recursion

• It makes  the code look more clean and elegant.
• Sequence creation is simpler through recursion than utilizing any nested iteration.
• Using recursion we can break complicated program into sub-programs.

Disadvantages of using recursion

• A lot of memory and time is taken through recursive calls which makes it expensive for use.
• Recursive functions are challenging to debug.
• The reasoning behind recursion can sometimes be tough to think through.

Syntax:

def func(): 
    ...
    ... (recursive call)
    ...
    
// calling function
func() 

Example:

def is_prime(i,n):
    if n == i:
        return 0
    else:
        if(n % i == 0):
            return 1
        else:
            return is_prime(i+1, n)

n = int(input("Enter your Number:"))

if(is_prime(2, n) == 0):
    print("It is a Prime Number.")
else:
    print("It is not a Prime Number.")

Output:

Enter your Number:4
It is not a Prime Number.