In Python, a function is a reusable block of code that performs a specific task. Functions help in organizing code, making it more readable and modular.
Here's a simple explanation with examples:
1. Function Definition:
```python
def greet(name):
"""This function greets the person passed in as a parameter."""
print(f"Hello, {name}!")
# Example usage:
greet("Alice")
```
In this example, `greet` is a function that takes a parameter `name` and prints a greeting.
2. Return Statement:
```python
def add(a, b):
"""This function adds two numbers and returns the result."""
sum_result = a + b
return sum_result
# Example usage:
result = add(3, 5)
print(result)
```
The `add` function adds two numbers and returns the result, which is then printed.
3. Default Parameters:
```python
def power(base, exponent=2):
"""This function raises the base to the power of the exponent."""
result = base ** exponent
return result
# Example usage:
result1 = power(3)
result2 = power(2, 4)
print(result1, result2)
```
The `power` function has a default value for `exponent`, which is 2 if not provided.
4. Keyword Arguments:
```python
def person_info(name, age, city):
"""This function prints information about a person."""
print(f"Name: {name}, Age: {age}, City: {city}")
# Example usage:
person_info(name="Bob", age=30, city="New York")
```
You can provide arguments by specifying the parameter names, making the code more readable.
5. Variable Scope:
```python
def modify_variable():
"""This function demonstrates variable scope."""
x = 10 # Local variable
print(f"Inside function: x = {x}")
x = 5 # Global variable
modify_variable()
print(f"Outside function: x = {x}")
```
The variable `x` inside the function is local, and it doesn't affect the global variable `x`.
These are basic examples, and Python functions can be more complex based on your needs. Functions enhance code reusability, readability, and maintainability.
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