Advantages of function in python
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Functions are an essential part of most programming languages. Functions are reusable pieces of code that can be called using a function's name. Functions can be called anywhere in a Python program,
including calling functions within other functions. Functions provide a couple of benefits: Functions allow the same piece of code to run multiple times Functions break long programs up into smaller components Functions can be shared and used by other programmers Every function has a function name. The function name is used when the function is called in a program. Calling a function means running a function. Functions can receive input from the program. The input provided to a function is called input arguments or just arguments. Arguments are the code passed to a function as input. Functions can produce output. We say a function returns output to the program. The output of a function can be assigned to a variable for use in a program. Below is an example calling Python's The function is a crucial concept in the world of programming. In this article, we’ll explore Python functions. You’ll learn why they are so important, how to define functions with Python’s def keyword, how to call functions, and we’ll learn about a topic that arises when using functions: variable scope. Table of contents
What is a function in Python?Let’s define what a function is, exactly: FunctionA Python function is a named section of a program that performs a specific task and, optionally, returns a valueFunctions are the real building blocks of any programming language. We define a Python function with the Advantages of using functionsCode reuseA Python function can be defined once and used many times. So it aids in code reuse: you don’t want to write the same code more than once. Functions are a great way to keep your code short, concise, and readable. By giving a function a well-chosen name, your code will become even more readable because the function name directly explains what will happen. This way, others (or future you) can read your code, and without looking at all of it, understand what it’s doing anyway because of the well-chosen function names. Other forms of code reuse are explained later on. E.g., you can also group code into modules and packages. ParametersFunctions accept a parameter, and you’ll see how this works in a moment. The big advantage here, is that you can alter the function’s behavior by changing the parameter. Return valuesA function can return a value. This value is often the result of some calculation or operation. In fact, a Python function can even return multiple values. Built-in Python functionsBefore we start defining functions ourselves, we’ll look at some of Python’s built-in functions. Let’s start with the most well-known built-in function, called >>> print('Hello, readers!')
Hello, readers!
>>> print(15)
15Print takes an argument and prints it to the screen. As stated in our
definition, functions can optionally return a value. However, >>> result = print('Hello')
Hello
>>> print(result)
None
Another built-in function, that does return a
value, is >>> mylength = len('Hello')
>>> print(mylength)
5Creating a Python functionNow that we know how to use a function let’s create a simple one ourselves. To do so, we use Python’s >>> def say_hi():
... print('Hi!')
...
>>> say_hi()
Hi!It’s just a few lines, but a lot is going on. Let’s dissect this:
IndentationPython uses indentation to distinguish blocks of code that belong together. Consecutive lines with equal indentation are part of the same block of code. To tell Python that the following lines are the body of our function, we need to indent them. You indent lines with the TAB key on your keyboard. In Python, it’s good style to use four spaces for indentation. The entire Python community does so. If you hit the TAB key, the Python interactive shell (REPL) and all decent editors will automatically indent with four spaces. Back to our function: it has only one line of code in its body: the print command. After it, we hit enter one extra time to let the Python REPL know that this is the end of the function. This is important. A function must always be followed by an empty line to signal the end of the function. Finally, we can call our function with Python function parameters and argumentsWe can make this more interesting by allowing an argument to be passed to our function. Again we define a function with def, but we add a variable name between the parentheses: >>> def say_hi(name):
... print('Hi', name)
...
>>> say_hi('Erik')
Hi ErikOur function now accepts a value, which gets assigned to the variable name. We call such variables the parameter, while the actual value we provide (‘Erik’) is called the argument. Parameters and argumentsA Python function can have parameters. The values we pass through these parameters are called arguments.As you can see, Python function with multiple argumentsLet’s make this even wilder and define a function with multiple arguments: >>> def welcome(name, location):
... print("Hi", name, "welcome to", location)
...
>>> welcome('Erik', 'this tutorial')
Hi Erik welcome to this tutorialIt’s not that hard; you just add more arguments to the function definition, separated by commas. Returning from a functionA function runs until the end of that function, after which Python returns to where the function was called from. In the following example, I want you to predict the output before you run it: Predict the output of this programDid your expectations match with reality? If so, you have a good understanding of how a function call works. Some people at this point expect to see the text “Let’s greet the entire world” twice. If you are one of them, don’t worry and keep reading. Python keeps track of the point where the function is called. In our case, it’s at line 5. Once called, Python runs the block of code inside the function line by line until it reaches the end of that function. And once the end of the function is reached, Python jumps back to the line right after where the function was called from: line 6! In short: a function call is not a jump or ‘go to’, but a call to a piece of reusable code, which returns to where it was called from. A function call is also an expression: most functions return a value. Returning valuesSo far, our function only printed something and returned nothing. What makes functions a lot more usable is the ability to return a value. Let’s see an example of how a Python function can return a value: This is how you return a value from a Python functionAs you can see, we use the keyword We could have used the function in an if statement as well. For example: if add(1, 1) == 2:
print("That's what you'd expect!")Empty return statementIf your function does not return anything, but you still want to return from the function, you can use an empty return statement. Here’s a silly example: def optional_greeter(name):
if name.startswith('X'):
# We don't greet people with weird names :p
return
print('Hi there, ', name)
optional_greeter('Xander')This is an interesting pattern; I call it returning early. I’d like to return early because the alternative is using blocks of if… else statements: def optional_greeter(name):
if name.startswith('X'):
# We don't greet people with weird names :p
pass
else:
print('Hi there, ', name)
optional_greeter('Xander')Which one do you feel looks cleaner? I’d say the first because it requires less indented code. And although the difference is small with such a small example, this starts to add up when you have bigger chunks of code. Variable scopeThe variable If we define a variable at the so-called top level of a program, it is visible in all places. Let’s demonstrate this: >>> def say_hi():
... print("Hi", name)
... answer = "Hi"
...
>>> name = 'Erik'
>>> say_hi()
Hi Erik
>>> print(answer)
Traceback (most recent call last):
File "
Default values and named parametersA compelling Python feature is the ability to provide default values for the parameters: >>> def welcome(name='learner', location='this tutorial'):
... print("Hi", name, "welcome to", location)
...
>>> welcome()
Hi learner welcome to this tutorial
>>> welcome(name='John')
Hi John welcome to this tutorial
>>> welcome(location='this epic tutorial')
Hi learner welcome to this epic tutorial
>>> welcome(name='John', location='this epic tutorial')
Hi John welcome to this epic tutorialOr, if you prefer, use the interactive example below: Demonstration of default values and named parametersBecause our parameters have a default value, you don’t have to fill them in. If you don’t, the default is used. If you do, you override the default with your own value. Calling Python functions while explicitly naming the parameters differs from what we did up until now. These parameters are called named parameters because we specify both the name and the value instead of just the value. Thanks to these named parameters, the order in which we supply them doesn’t matter. If you think about it, it’s the natural and only way to make default values useful. If you don’t want to use named parameters, you can. When you rely on position instead of names, you provide what we call positional parameters. The position matters, as can be seen below: >>> def welcome(name='learner', location='this tutorial'):
... print("Hi", name, "welcome to", location)
...
>>> welcome('Erik', 'your home')
Hi Erik welcome to your homeFor now, you’ve learned enough about functions to continue with the tutorial. If you like to learn more, read my Python functions deep dive. Are you enjoying this free tutorial? Please also have a look at my premium courses. They offer a superior user experience with small, easy-to-digest lessons and topics, progress tracking, quizzes to test your knowledge, and practice sessions. Each course will earn you a downloadable course certificate. What are the advantages of using functions?By using functions, we can avoid rewriting same logic/code again and again in a program. We can call C functions any number of times in a program and from any place in a program. We can track a large C program easily when it is divided into multiple functions. Reusability is the main achievement of C functions.
What are the features of Python functions?We have listed below a few essential features.. 1) Easy to Learn and Use. Python is easy to learn as compared to other programming languages. ... . 2) Expressive Language. ... . 3) Interpreted Language. ... . 4) Cross-platform Language. ... . 5) Free and Open Source. ... . 6) Object-Oriented Language. ... . 7) Extensible. ... . 8) Large Standard Library.. What are the advantages and disadvantages of Python?Comparison Table for Advantages and Disadvantages of Python. What are the most useful functions in Python?Some of the most useful functions in Python are print(), abs(), round(), min(), max(), sorted(), sum(), and len().
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