Functions

A function is a block of reusable code that performs a specific task. Think of a function as a mini-program within your main program. It helps you organize your code and make it more modular.

To define a function, you use the def keyword followed by the name of the function and parentheses (). Here's an example:

def greet():
    print("Hello, how are you?")

In this example, we defined a function called greet(). Whenever this function is called, it will print the message "Hello, how are you?".

To call or use a function, you simply write its name followed by parentheses (). For example:

greet()  # Output: "Hello, how are you?"

In this code, we called the greet() function, and it printed the message "Hello, how are you?".

Functions can also accept parameters, which are values that you can pass to the function when calling it. Parameters help you make your functions more flexible and reusable. Here's an example:

def greet(name):
    print("Hello, " + name + "! How are you?")

In this example, we defined a function called greet() that accepts a parameter called name. When calling this function, you need to provide a value for the name parameter. For example:

greet("John")  # Output: "Hello, John! How are you?"

In this code, we called the greet() function and passed the value "John" as the name parameter. The function then printed the message "Hello, John! How are you?".

Functions can also return values using the return keyword. This allows us to get a result or output from a function. Here's an example:

def add_numbers(a, b):
    return a + b

In this example, we defined a function called add_numbers() that accepts two parameters a and b. The function returns the sum of a and b. To use the result of this function, you can assign it to a variable or use it in an expression. For example:

result = add_numbers(5, 3)
print(result)  # Output: 8

In this code, we called the add_numbers() function with the values 5 and 3. The function returned the sum 8, which we assigned to the variable result and then printed.

These are just some basic concepts of functions in Python. Functions can be much more complex and can have multiple parameters, perform calculations, and even call other functions.