What is the default input in python with example

Frieda 187 Published: 07/24/2024

What is the default input in python with example

I'll respond in English for now.

In Python, when you run a script without specifying any input files or arguments, it will execute as if you had provided the input() function's default value as an argument. This is known as "default input" or "default argument."

Let's see this with an example:

def greet(name = "World"):

print(f"Hello, {name}!")


greet()  # Output: Hello, World!

In the above code snippet, name is a function parameter that defaults to "World" if no value is provided. When we call the greet() function without passing any arguments (like greet()), Python will automatically pass the default value "World" as an argument to the function.

This behavior can be useful when you want your program to have some default behavior or settings that can be overridden by the user if needed. For example:

def calculate_total(prices = [0, 0]):

total_price = sum(prices)


return total_price


total = calculate_total()


print(total)  # Output: 0 (since prices is an empty list)

You can override the default values by providing a custom input

custom_prices = [10, 20]


total = calculate_total(custom_prices)


print(total)  # Output: 30 (the sum of the custom prices)

In this example, we're using the prices parameter as an optional input. When called without any arguments (calculate_total()), Python will execute with default values for prices, which is an empty list [0, 0]. If you want to calculate the total price based on some specific prices, you can override the default by providing your own custom prices.

Remember, when writing functions in Python, using default input (or arguments) allows you to make your code more flexible and easier to use.

Python default value if None function

I see what's going on here! You're asking me to respond in English only and write about the default values in Python, specifically when it comes to the None function.

Well, let's dive right into it!

In Python, the built-in value for None is used to indicate a missing or undefined value. This can be particularly useful when you need to represent an optional parameter, return value, or variable that might not always have a valid value. By using None, you can ensure your code remains robust and easy to understand.

Let's look at some examples to illustrate how None works:

Function defaults: Imagine you have a function that takes two arguments, but one of them is optional. You can set the default value for the second argument as None. This way, when calling the function without providing a value for the second argument, it will automatically assume None.

Example:

def greeting(name: str = None) -> str:

if name is None:


return "Hello, world!"


else:


return f"Hi, {name}!"


print(greeting())  # Output: Hello, world!


print(greeting("John"))  # Output: Hi, John!
Return values: When a function doesn't need to return any value or when it's not applicable in certain situations, you can set the return type as None. This way, if the function encounters an error or an undefined scenario, it will simply return None without raising an exception.

Example:

def search_database(query: str) -> None:
Perform database query...

if result:


print(result)


else:


return None


search_database("John")  # Output: None
Variable assignments: In some cases, you might need to assign a value to a variable that doesn't always have a valid value. This is where None comes in handy! When assigning a variable without an explicit value, it will automatically assume the value of None.

Example:

result = None

print(result)  # Output: None

Later on...

if result is not None:


print(f"Found something: {result}")


else:


print("No result found!")

In conclusion, Python's None function provides a flexible and efficient way to handle optional values in your code. By using it judiciously, you can create robust, readable, and maintainable programs that are easy to work with.

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