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Function Arguments in Python

 

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Function Arguments in Python

In Python, functions can accept arguments to pass data and variables. Understanding different types of function arguments helps write more flexible and powerful functions. There are several types of arguments that can be used in Python functions:

1. Positional Arguments

Positional arguments are the most common type of arguments in Python. The order in which the arguments are passed matters.

# Function with positional arguments
def add(a, b):
    return a + b

# Calling the function
result = add(5, 3)
print(result)  # Output: 8

2. Keyword Arguments

Keyword arguments are passed by explicitly stating the parameter name and value. This allows for arguments to be passed in any order.

# Function with keyword arguments
def greet(name, message):
    print(message + ", " + name + "!")

# Calling the function
greet(message="Good morning", name="Bob")  # Output: Good morning, Bob!

3. Default Arguments

Default arguments allow parameters to have a default value if no value is provided during the function call.

# Function with default arguments
def greet(name, message = "Hello"):
    print(message + ", " + name + "!")

# Calling the function
greet("Alice")  # Output: Hello, Alice!
greet("Bob", "Good morning")  # Output: Good morning, Bob!

4. Variable-Length Arguments

Python allows functions to accept variable-length arguments using *args for non-keyword arguments and **kwargs for keyword arguments.

# Function with *args
def sum_all(*args):
    total = 0
    for num in args:
        total += num
    return total

# Calling the function
result = sum_all(1, 2, 3, 4)
print(result)  # Output: 10
    

# Function with **kwargs
def print_info(**kwargs):
    for key, value in kwargs.items():
        print(f"{key}: {value}")

# Calling the function
print_info(name="Alice", age=25, city="Wonderland")

5. Keyword-Only Arguments

Keyword-only arguments are specified after a single asterisk * in the function definition. These arguments can only be passed using their keyword.

# Function with keyword-only arguments
def greet(name, *, message = "Hello"):
    print(message + ", " + name + "!")

# Calling the function
greet("Alice")  # Output: Hello, Alice!
greet("Bob", message = "Good evening")  # Output: Good evening, Bob!

6. Positional-Only Arguments

Positional-only arguments are specified before a single forward slash / in the function definition. These arguments can only be passed by position.

# Function with positional-only arguments
def subtract(a, b, /):
    return a - b

# Calling the function
result = subtract(10, 3)
print(result)  # Output: 7

7. Combining Argument Types

Different types of arguments can be combined in a single function definition. The order should be: positional-only arguments, positional arguments, *args, keyword-only arguments, and **kwargs.

# Combining different types of arguments
def combined_example(a, b, /, *, c, **kwargs):
    print(f"a: {a}, b: {b}, c: {c}")
    for key, value in kwargs.items():
        print(f"{key}: {value}")

# Calling the function
combined_example(1, 2, c = 3, d = 4, e = 5)
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