How to use Function in Python

Python Function

• Group of statements that together perform a specific task. 
• It defines the behavior of a class
• Implementation of variables
• Function can have a list of formal parameters and may or may not a return value
• In python, the function can be created with help of def keyword

TYPES OF FUNCTION

• Python supports two types of functions. They are:
  • Built-in function or pre-defined function or library function
  • User defined function.

1. Pre-defined function (Built-in function)

• It is already created by developer and added in python library
• Once python modules are imported, then user can access its predefined functions in the code
• No need to provide any implementation (definition) for this pre-defined function. Because its definition is already created and attached with corresponding python modules.
• Example
•   print(), input(), etc, …

2. User defined function

• Here function is created by programmer or user
• The def keyword is used to create one or more number function in python language
• The keyword def is used to start and declare a function. A colon (:) operator must be marked at the end of function declaration
• It is called by using its name.

INVOKING FUNCTION

• Process of activating a method is called invoking or calling.
• In python, the function is called by using its name.

I. FUNCTION WITH NO ARGUMENTS

(test.py)

1. SOURCE CODE

2. OUTPUT

II. FUNCTION WITH ARGUMENTS

(test.py)

1. SOURCE CODE

# creating a function

def add(x,y):

     c=x+y

     print(“Sum is : “,c)

# calling a function

add(10,5)

2. OUTPUT

RETURN STATEMENT

• Like c++/java, python supports return statement
• The return expression is used to send the output from called function to calling function (caller function)
• It will return nothing, if no expression is given after the return statement
• Unlike c++/java/c#,  python returns multiple values which are types of tuples.

III. FUNCTION WITH ARGUMENTS AND RETURN STATEMENT

(test.py)

1. SOURCE CODE

2. OUTPUT