Python is a widely-used programming language that has a variety of built-in functions and libraries that make it a powerful tool for developers.
Functions are one of the fundamental building blocks of any programming language, and Python is no exception. Python functions can be broadly classified into two categories: pre-defined functions and user-defined functions.
In this blog, we will explore the differences between these two types of functions and how they are used in Python programming. Let’s begin by understanding what are the two key types of python functions.
Types of Functions
In this blog, we will be talking about the following two types of python functions.
Pre-defined functions (Inbuilt/Library function)
User-defined functions (Custom function)
Pre-defined functions, also known as built-in functions, are functions that come pre-packaged with Python. These functions are already implemented in the language, so you can use them without having to write any code. Some examples of pre-defined functions in Python include print(), input(), len(), and range().
Python also comes with a vast collection of libraries that provide additional pre-defined functions for developers. These libraries include NumPy, Pandas, Matplotlib, and many others. Each library provides a set of functions that are designed to solve specific problems, such as data analysis, data visualization, or machine learning.
Predefined functions examples
print(), len(), str() etc
User-defined functions, also known as custom functions, are functions that you create yourself. These functions can be used to perform a specific task or set of tasks that you define. User-defined functions are written in Python and can be called from anywhere in your code.
To create a user-defined function in Python, you must first define the function using the def keyword, followed by the function name, and any parameters the function requires. Once the function is defined, you can call it from anywhere in your code by using its name and passing in any necessary arguments.
User-defined functions examples
printsum(a,b), printName(“name”) etc
Need of Functions
There is always a great need for functions in python, below I have listed the top 3 crucial reasons why we need functions.
DRY – Don’t repeat yourself
Syntax of a Function in Python
def function_name(parameters) -> return_type:
Explanation of Function Syntax
Here the def keyword is used to mark that the following code is part of the definition of a function and certain rules will be followed here.
The function_name is defined by which the function so created will be called.
A function can have n number of arguments passed to it where n can vary between 0 to any greater number. Parameters can be of named and not named type.
The return type is an optional part where if we don’t want the function to return any specific type then we don’t need to define it. But if we want to make the function return a specific type of value then we should define the return type which binds the function to return only the specific type value otherwise it will return an exception.
The function body is the part where the code for the operation that the function will perform is defined. It can be a single line or multiple lines.
Different Types of Methods
Method without params
Method with known number of params
Method with unknown number of params
Method with Keyword Arguments
Method with unknown number of Keyword Arguments
The method without params:
This is the method in which no argument is in requirement to carry out the operation/code that has to execute. Eg method returning current DateTime.
Here we know how many params we will be sending and defining beforehand to return the required response.
The method with an unknown number of Params
Methods where the number of arguments is not-define beforehand and can vary in such cases we define the arguments with an * sign before the argument name and it will convert the params into a tuple of params. Like in the case of a function returning the average of numbers passed to it.
def averages(*numbers): sum = 0 num = len(numbers) for num in numbers: sum = sum + num return sum/num
Here we can pass any number of arguments, eg 2 or 20 and it will return us an average of the numbers passed to this function.
The method with Keyword Arguments
Method where the arguments are passing as key and value. In these methods, the order of params does not matter.
The method with an unknown number of Keyword Arguments:
Method where there is a number of arguments but the number is unspecified or unknown at the time of definition and uses keyword arguments in those cases we can add **(double asterisk) before the parameter name to handle the list of named parameters, for example:
The following are some of the special types of functions in the python programming language:
Python functions are an essential component of any Python program. Pre-defined functions are functions that come built-in with Python, while user-defined functions are functions that you create yourself. Pre-defined functions provide a powerful set of tools that you can use to solve a wide range of problems, while user-defined functions allow you to create custom functionality tailored to your specific needs.
Understanding the differences between these two types of functions and how they are in use in Python programming is crucial for any developer looking to build robust and efficient applications. By leveraging the power of pre-defined functions and creating custom user-defined functions, you can create powerful and flexible applications that can tackle a wide range of challenges.