Why do we use default arguments in Python function definitions?

We use default arguments in python function definitions to provide a default value for an argument that can be overridden by the caller. This can be useful for providing flexibility in the use of the function and to make the code more readable and concise by avoiding unnecessary repetitive arguments.

For example, imagine a function that takes three arguments, but in some cases, one of the arguments has a commonly used default value. Instead of needing to specify that argument for each call to the function where that default value is appropriate, we can define it once as a default argument. That way, we can omit the argument when calling the function and it will automatically use the default value, but we still have the option to override that default value by explicitly providing a value for that argument. Here is an example of how to define a function with default arguments in Python.

def my_function(a, b, c=0):
    # do something with a, b, and c
    print(a + b + c)

In the above example, c is a default argument with a default value of 0. This means that when calling the function my_function without a third argument, it will use the default value of 0 for c.

To define default values for function arguments in Python

To define default values for function arguments in Python, you can simply assign default values to the function parameter when it is defined. Here is an example:

def my_function(a, b, c=0):
    # Do something with a, b, and c
    return a + b + c

In the above example, the c parameter has a default value of 0. This means that if we call my_function(1, 2) without providing a value for c, it will use the default value of 0. However, we can still provide a different value for c if we want, like my_function(1, 2, 3).

To set default parameter types in Python, you can use type hints. Type hints allow you to specify the expected data type of a function’s arguments and return value. Here is an example:

def my_function(a: int, b: int, c: float = 0.0) -> float:
    # Do something with a, b, and c
    return a + b + c

In the above example, a and b are expected to be integers, and c is expected to be a float. The return value is also expected to be a float. If you pass an argument of the wrong type to the function, Python will raise a TypeError.

Using default values and type hints in this way can make your code more concise, readable, and robust.