We shall study Python functions in this manual. A piece of code known as a function is used to carry out a particular task and contains one or more Python statements.
Why would Python use a function?
A function, as I indicated before, is a section of code that carries out a particular duty. Let’s talk about what our code can accomplish utilizing functions in Python:
1. Reusability of code: Assume that when building a Python program, we must write 10 lines of code in order to accomplish each of the specified tasks that must be completed. Because writing those 10 lines of code every time you perform that action is cumbersome, it would make your code lengthier, less readable, and increase the likelihood of human mistake. It would be preferable to write those 10 lines of code in a function and simply call the function whenever it is required.
2. Enhances Readability: By employing functions for recurring activities, you structure and improve the readability of your code. Anyone looking at the code would find it simpler to comprehend the logic and goal.
3. Eliminate redundancy: By substituting functions for repeated lines of code in your code, you can eliminate any duplication that might have been introduced by not utilizing functions.
Python function syntax
Declaration of a function:
def function_name(function_parameters): function_body # Set of Python statements return # optional return statement
Calling the function:
# when function doesn't return anything function_name(parameters)
# when function returns something # variable is to store the returned value variable = function_name(parameters)
Python function illustration
Here, the add() function adds the two numbers that are sent to it as inputs. In our application, we call the function twice after function declaration to perform the addition.
def add(num1, num2): return num1 + num2 sum1 = add(100, 200) sum2 = add(8, 9) print(sum1) print(sum2)
Function default arguments
Knowing how to declare and call a function now, let’s look at how to use the default arguments. We may prevent the mistakes that might occur when calling a function without giving all the parameters by utilizing default arguments. To further grasp this, let’s look at an example:
In this example, we’ve given the default argument for the second parameter, which will be utilized if the second parameter is omitted when using this function.
# default argument for second parameter def add(num1, num2=1): return num1 + num2 sum1 = add(100, 200) sum2 = add(8) # used default argument for second param sum3 = add(100) # used default argument for second param print(sum1) print(sum2) print(sum3)
300 9 101
Kinds of operations
In Python, there are two categories of functions:
1. Built-in functions: These are predefined functions in Python that do not require declaration before use. We are free to call upon them as and when we see fit.
2. User-defined functions: These are the functions that we write in our code. In the examples above, we established a user-defined method called add().
In the individual guides, we will go over various function types in more detail.