Why Does My Recursive Function Sometimes Return None?

Why Does Recursive Function Return None?

In your provided code, the get_input() function confronts an issue where it returns None occasionally. This occurs when the user enters an invalid value initially and then enters "a" or "b." To understand why, let's examine the function in more detail.

The function get_input() prompts the user to enter "a" or "b." If the input doesn't match, it prints a message and recursively calls itself to get input again. This recursive flow ensures that the user provides a valid input.

The issue arises in the if statement inside the function. When the user initially enters an invalid value and the function calls itself recursively, the recursive call doesn't return anything. Instead, it falls off the end of the function.

In Python, falling off the end of a function is equivalent to returning None. This means that the get_input() function returns None when the user first enters an invalid value.

To fix this issue, you need to ensure that the recursive call returns a value. In your if statement, replace the following line:

get_input()

With the following:

return get_input()

This modification ensures that the recursive call returns the result of the subsequent call, which will be the proper input ("a" or "b") or None if the user keeps entering invalid values.

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