What is required for a function to be considered recursive?

For a function to be considered recursive, it is essential that it calls itself either directly or indirectly. This self-referential behavior is the defining characteristic of recursion. In a direct recursion scenario, the function explicitly calls itself within its body. In an indirect recursion scenario, a function may call another function that eventually leads back to the original function.

This characteristic allows recursive functions to break down complex problems into simpler sub-problems, which makes it easier to achieve a solution. For example, calculating the factorial of a number can be expressed recursively by defining the factorial of a number in terms of the factorial of the previous number.

While having a base case is a crucial part of most recursive functions to ensure they terminate properly, the mere presence of a base case does not define a function as recursive. Similarly, recursive functions can also coexist with loops, so utilizing loops does not prohibit recursion. Therefore, the essence of recursion lies in the function’s ability to call itself, either directly or indirectly.