How to Use def in Python With Example

Categories Python

In Python, the def keyword is used to define a function. Functions are blocks of reusable code that perform a specific task when called. Defining functions allows you to modularize your code, making it more organized, readable, and easier to maintain. Here’s the basic syntax for defining a function in Python

 def function_name(parameters):
    # Function body (code block)
    # You can have one or more statements here
    # Return a value using the 'return' keyword (optional)Code language: Python (python)

Let’s break down the elements of this syntax:

  • def: This keyword signals the start of a function definition.
  • function_name: Choose a unique name for your function. The function name should follow Python’s naming conventions and be descriptive of what the function does. Avoid using reserved keywords or built-in function names as your function name.
  • parameters: This is a comma-separated list of input parameters that the function can accept. Parameters are like placeholders that allow you to pass values into the function when it’s called. You can have zero or more parameters.
  • Function body: The block of code indented below the def statement represents the function’s body. It contains the instructions that will be executed when the function is called.
  • return (optional): If you want your function to return a value, use the return statement followed by the value you want to return. If the return statement is not used, the function will return None by default.

Here’s an example of a simple function that takes two numbers as input and returns their sum:

 def add_numbers(num1, num2):
    sum_result = num1 + num2
    return sum_result

# Call the function and store the result in a variable
result = add_numbers(5, 3)
print(result)  # Output: 8
Code language: Python (python)

To use the def keyword effectively, think about the tasks you want your code to perform and consider whether breaking them down into functions will make the code more organized and maintainable. Functions can be defined anywhere in your Python code, but it’s generally a good practice to define them before they are called.

Remember to use proper indentation to define the function body correctly, as Python relies on indentation for defining code blocks.

How to get data from def in Python?

To get data from a function in Python, you can use the return statement. The return statement allows a function to send a value or a collection of values back to the code that called it. Here’s an example:

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

# Calling the function and storing the returned value
sum_result = add_numbers(5, 3)
print(sum_result)  # Output: 8
Code language: Python (python)

In the above example, the add_numbers function takes two parameters, a and b, and computes their sum.

The result is stored in the result variable, and then the function uses the return statement to send that value back to the caller.

When calling the add_numbers function with arguments 5 and 3, the returned value is assigned to the variable sum_result, which can be used to access the computed sum outside the function.

You can also return multiple values from a function by separating them with commas:

def get_name():
    first_name = "John"
    last_name = "Doe"
    return first_name, last_name

# Calling the function and storing the returned values
first, last = get_name()
print(first)  # Output: John
print(last)   # Output: Doe
Code language: Python (python)

In this example, the get_name function returns two values: first_name and last_name. When calling the function and storing the returned values in the variables first and last, we can access each value individually.

What is def Myfunc () in Python?

In Python, def Myfunc() is the syntax used to define a function named Myfunc without any parameters. Here’s an example:

def Myfunc():
    # Function body (instructions)
    # ...
    # ...
Code language: Python (python)

In this case, Myfunc is the name of the function, and the parentheses () indicate that the function does not take any parameters.

You can write your desired instructions inside the function body. These instructions will be executed when the function is called.

Here’s an example of defining and calling the Myfunc function:

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

# Calling the function
Myfunc()  # Output: Hello, World!
Code language: Python (python)

In this example, the Myfunc function simply prints “Hello, World!” when called.

When executing Myfunc(), the function is invoked, and it executes the instructions within its body, resulting in the message being printed.

Note that without any parameters, the function Myfunc cannot accept any input values. If you need to pass arguments to a function, you can define the function with parameters inside the parentheses.

For example, def Myfunc(arg1, arg2) would define a function with two parameters, arg1 and arg2.

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  • Dmytro Iliushko

    I am a middle python software engineer with a bachelor's degree in Software Engineering from Kharkiv National Aerospace University. My expertise lies in Python, Django, Flask, Docker, REST API, Odoo development, relational databases, and web development. I am passionate about creating efficient and scalable software solutions that drive innovation in the industry.

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