What are recursive functions?

Recursive functions or recursion is a process when a function calls a copy of itself to work on smaller problems.

Recursion is the process in which a function calls itself directly or indirectly. The corresponding function which calls itself is called a recursive function.

• Any function which calls itself is called a recursive function.
• This makes the life of a programmer easy by dividing a complex problem into simple or easier problems.
• A termination condition is imposed on such functions to stop them from executing copies of themselves forever or infinitely. This is also known as the base condition.
• Any problem which can be solved recursively can also be solved iteratively.
• Recursions are used to solve tougher problems like Tower Of Hanoi, Fibonacci Series, Factorial finding, etc., and many more, where solving by intuition becomes tough.

What is a base condition?

The case in which the function doesn’t recur is called the base case.

For example, when we try to find the factorial of a number using recursion, the case when our number becomes smaller than 1 is the base case.

Recursive Case

The instances where the function keeps calling itself to perform a subtask, which is generally the same problem with the problem size reduced to many smaller parts, is called the recursive case.

Example of recursion:

#include <stdio.h>
 
int factorial(int num)
{
    if (num > 0)
    {
        return num * factorial(num - 1);
    }
    else
    {
        return 1; // Corrected to return 1 for factorial base case
    }
}
 
int main()
{
    int ans = factorial(10);
    printf("%d", ans);
    return 0;
}

Output:

3628800