Function Arguments

 Here is a detailed explanation of function arguments in Python with examples:

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1. No Argument

• A function with no parameters takes no arguments when called.

Example:

def greet():
    print("Hello, World!")

greet()

Output:

Hello, World!

In this example, the greet() function does not require any arguments.

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2. Required Arguments (Positional Arguments)

• These arguments must be passed in the correct order when calling the function.
• Missing any required arguments will result in an error.

Example:

def greet(name, age):
    print(f"Hello {name}, you are {age} years old.")

greet("Alice", 25)  # Correct
greet(25, "Alice")  # Incorrect order

Output:

Hello Alice, you are 25 years old.
Hello 25, you are Alice years old.

Error if an argument is missing:

greet("Alice")  # Missing 'age' argument

Error:

TypeError: greet() missing 1 required positional argument: 'age'

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3. Arbitrary Length Argument (*args)

• If you are unsure about the number of arguments, use *args to accept any number of positional arguments.
• The *args parameter collects the arguments into a tuple.

Example:

def add_numbers(*args):
    total = sum(args)  # Sum all values in args
    print(f"Sum of numbers: {total}")

add_numbers(1, 2, 3)       # 3 arguments
add_numbers(10, 20, 30, 40)  # 4 arguments

Output:

Sum of numbers: 6
Sum of numbers: 100

Here, *args allows you to pass any number of arguments, which are collected as a tuple.

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4. Keyword Arguments

• Keyword arguments are passed with the parameter name explicitly specified.
• The order of arguments does not matter.

Example:

def greet(name, age):
    print(f"Hello {name}, you are {age} years old.")

greet(age=25, name="Alice")  # Keyword arguments

Output:

Hello Alice, you are 25 years old.

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5. Default Arguments

• Default arguments have a predefined value in the function definition.
• If a value is not provided during the function call, the default value is used.

Example:

def greet(name, age=18):  # Default value for 'age'
    print(f"Hello {name}, you are {age} years old.")

greet("Alice")         # Uses default age (18)
greet("Bob", 25)       # Overrides default age

Output:

Hello Alice, you are 18 years old.
Hello Bob, you are 25 years old.

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Combination of Argument Types

You can combine all these argument types in a function, but they must follow a specific order:

Order:

1. Required arguments (positional)
2. Default arguments
3. Arbitrary length arguments (*args)
4. Keyword arguments
5. Arbitrary keyword arguments (**kwargs)

Example:

def demo_function(a, b=10, *args, name="Anonymous", **kwargs):
    print(f"Positional: a={a}, b={b}")
    print(f"*args: {args}")
    print(f"Keyword argument: name={name}")
    print(f"**kwargs: {kwargs}")

demo_function(1, 20, 30, 40, name="Alice", city="New York", age=25)

Output:

Positional: a=1, b=20
*args: (30, 40)
Keyword argument: name=Alice
**kwargs: {'city': 'New York', 'age': 25}

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Summary Table

Argument Type	Syntax	Description	Example
No Argument	def func():	Function without any parameters.	func()
Required Argument	def func(a, b):	Arguments that must be provided.	func(1, 2)
Arbitrary Length Argument	def func(*args):	Accepts any number of positional arguments.	func(1, 2, 3) → args=(1, 2, 3)
Keyword Argument	def func(name):	Arguments passed using parameter names.	func(name="Alice")
Default Argument	def func(a=10):	Parameters with default values.	func() → Default, func(5) → Overrides.

Let me know if you'd like further examples or clarification! 😊