USER DEFINED FUNCTION
IN PYTHON
MALLA REDDY ENGINEERING COLLEGE
Submitted To:
Submitted By:
Gujjula Divya
22J41A0521
Computer Science and Engineering
INTRODUCTION:
A function is a block of program statements which can be used repetitively in a
program. It saves the time of a developer. There are some built-in functions which part of
python.
TYPES OF FUNCTIONS IN PYTHON:
➢ Built-in functions:
Python provides a set of built-in functions like ‘print ()’, ’len()’ , ‘type’ , etc., which are
available for use without any additional effort.
➢ User-defined functions:
user-defined functions are those that users create to perform specific tasks. These
functions are defined using the ‘def’ keyword followed by the function name and
parentheses ‘()’.
CREATING USER-DEFINED FUNCTIONS:
Syntax:
def function_name(parameters):
"""docstring"""
statement(s)
EXAMPLE:
def greet(name):
return f"Hello, {name}!"
PARAMETERS AND ARGUMENTS:
Functions can accept parameters to make them more flexible.
RETURN STATEMENT:
Functions can return values using the `return` statement.
EXAMPLES OF USER-DEFINED FUNCTIONS:
➢ Simple Function with No Parameters:
def greet ():
return "Hello, World!"
➢ Function with Parameters:
def greet(name):
return f"Hello, {name}!"
➢ Function with a Return Value:
def add(x, y):
return x + y
➢ Function with Default Parameter Values:
def greet(name="World"):
return f"Hello, {name}!"
➢ Function with Variable-Length Arguments:
def sum_all(*args):
return sum(args)
ADVANCED TOPICS:
➢ Recursive Functions:
Functions that call themselves are known as recursive functions.
def factorial(n):
if n == 0 or n == 1:
return 1
else:
return n * factorial(n-1)
➢ Lambda Functions:
Lambda functions are small anonymous functions.
square = lambda x: x ** 2
EXAMPLE: CALCULATOR APPLICATION
It implements a basic calculator with functions for addition, subtraction, multiplication,
division, power calculation, and factorial calculation.
➢ Function to add two numbers
def add (num1, num2):
return num1 + num2
➢ Function to subtract two numbers
def subtract (num1, num2):
return num1 - num2
➢ Function to multiply two numbers
def multiply (num1, num2):
return num1 * num2
➢ Function to divide two numbers
def divide (num1, num2):
return num1 / num2
print ("Please select operation -\n" \
"1. Add\n" \
"2. Subtract\n" \
"3. Multiply\n" \
"4. Divide\n")
➢ Take input from the user
select = int (input ("Select operations form 1, 2, 3, 4:"))
number_1 = int (input ("Enter first number: "))
number_2 = int (input ("Enter second number: "))
if select == 1:
print (number_1, "+", number_2, "=",
add (number_1, number_2))
elif select == 2:
print (number_1, "-", number_2, "=",
subtract (number_1, number_2))
elif select == 3:
print (number_1, "*", number_2, "=",
multiply (number_1, number_2))
elif select == 4:
print (number_1, "/", number_2, "=",
divide (number_1, number_2))
else:
print ("Invalid input")
Output:
Please select operation -
1. Add
2. Subtract
3. Multiply
4. Divide
Select operations form 1, 2, 3, 4: 1
Enter first number: 15
Enter second number: 14
15 + 14 = 29
CONCLUSION:
User-defined functions are crucial for writing efficient and modular code. They help in
breaking down complex problems into smaller, manageable tasks.
