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Function

A function is a block of organised and reusable code used to perform a single or related action. Functions receive data in
the form of arguments and use it to run a specified set of statements and produce the final output.

Features of Function
Some important features of functions are:

u A program is divided into small modules and each module performs some specific task. Each module can be called as
per the requirement.
u We can call a function as many times as required. This saves the programmer the time and effort to rewrite the same
code again. Therefore, it also reduces the length of the program.
u Dividing a bigger program into smaller functions makes the program more manageable. It makes debugging easy
and makes the code efficient, both in terms of time and memory.

Components of Python Function

A Python function consists of the following components:
u Name of the function: A function name should be unique and easy to correlate with the task it will perform. We can
have functions of the same name with different parameters.
u Arguments: The input given to the functions are referred to as arguments. A function can or cannot have any
arguments.
u Statements: The statements are the executable instructions that the function can perform.
u Return Value: A function may or may not return a value.

Advantages of Functions

Following are the advantages of functions:
u You can write Python program in logically independent sections.
u Functions provide better modularity for your application and a high degree of code reusing.
u As the program grows larger, functions make it more organized and manageable.
u The complexity of a program can be divided into simple subtasks and function subprograms can be written for every
subtasks.
u Multiple persons can work on same program by assigning different functions to each of them.
u In Python, a function can call the same function again and again, called as recursiveness.
u You could also bring in other libraries or modules to your program that contain pre-defined functions readily available
for use.

Types of Functions in Python
We have mentioned earlier that one of the strengths of the Python language is that Python functions are easy to define
and use. Python functions can be categorised into built-in functions and user-defined functions. Let us discuss about
them in detail.

Built-In Functions
The print( ) and input( ) belong to the category of built-in functions. We also have other built-in functions like range( ),
type( ), etc. The main difference between these two categories is that built-in functions do not require to be written by us
whereas a user-defined function has to be developed by the user at the time of writing a program.

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