What are Functions?

• Code Block: A function is a reusable block of code designed to perform a specific task.

• Organization: Functions help break down your code into modular, manageable units.

• Inputs and Outputs: Functions can take inputs (called arguments or parameters) and may return an output.

Why Use Functions?

• Reusability: Write a function once, and call it multiple times from different parts of your code.

• Readability: Well-named functions make code easier to understand and maintain.

• Abstraction: Functions hide implementation details, allowing you to focus on the overall logic of your program.

• Testing: It's easier to test smaller, isolated functions.

Basic Syntax

Python

def function_name(parameter1, parameter2, ...):
    """
    This is the docstring (optional, but good practice)
    Describes what the function does.
    """
    # Function code here
    # ....
    return output_value  # Optional, can return a value

Example

Python

def greet(name):
    """Greets a person by name."""
    print("Hello,", name + "!")

greet("Alice")  # Outputs: Hello, Alice!

Key Points

• def keyword: Used to define a function.

• Docstrings: Explanatory strings within triple quotes (""") below the function definition.

• Parameters: Variables that receive values when the function is called.

• return statement: Sends a value back from the function (optional).

Types of Functions

• Built-in Functions: Python provides many ready-to-use functions like print(), len(), min(), etc.

• User-defined Functions: Functions you create yourself like the greet() example above.

Example with Input and Output

Python

def calculate_area(length, width):
    """Calculates the area of a rectangle."""
    area = length * width
    return area

result = calculate_area(5, 10)
print("The area is:", result)  # Outputs: The area is: 50

Example 1: Area Calculations

Python

def calculate_rectangle_area(length, width):
    """Calculates and returns the area of a rectangle."""
    area = length * width
    return area

def calculate_circle_area(radius):
    """Calculates and returns the area of a circle."""
    pi = 3.14159
    area = pi * radius * radius
    return area

# Get user input
shape = input("Enter shape (rectangle or circle): ")

if shape == "rectangle":
    length = float(input("Enter length: "))
    width = float(input("Enter width: "))
    area = calculate_rectangle_area(length, width)
elif shape == "circle":
    radius = float(input("Enter radius: "))
    area = calculate_circle_area(radius)
else:
    print("Invalid shape")

print("The area is:", area)

Example 2: Student Grading

Python

def determine_grade(score):
    """Assigns a letter grade based on a numerical score."""
    if score >= 90:
        return "A"
    elif score >= 80:
        return "B"
    elif score >= 70:
        return "C"
    elif score >= 60:
        return "D"
    else:
        return "F"

# Get student information
student_name = input("Enter student name: ")
score = int(input("Enter score: "))

grade = determine_grade(score)
print(student_name, "earned a grade of", grade)

Example 3: Password Checker

Python

def check_password(password):
    """Checks if a password meets complexity requirements."""
    has_upper = False
    has_lower = False
    has_digit = False

    for char in password:
        if char.isupper():
            has_upper = True
        if char.islower():
            has_lower = True
        if char.isdigit():
            has_digit = True

    if len(password) >= 8 and has_upper and has_lower and has_digit:
        return True
    else:
        return False

# Get password from the user
password = input("Enter a new password: ")

if check_password(password):
    print("Password is strong.")
else:
    print("Password is weak. Please follow complexity rules.")

Key Points

• Arguments: Values passed to functions when they are called.

• Flexibility: Functions with arguments make our code reusable for different inputs.

• Modularity: Breaking down problems into smaller, well-defined functions.

01 How to Install Anaconda Software : https://youtu.be/gy7H0AsgfxY
02 What are variables in Python : https://youtu.be/Hpr-u35kz84
03 Int float Boolean Data types : https://youtu.be/H76ye6GVwZY
04 String data type : https://youtu.be/Ow9gJAlbzpk
05 Arithmetic Operators in Python : https://youtu.be/jJl50Tg070Y
06 Python Comparison Operators : https://youtu.be/psV3lnKXKUU
07 Logical and Identity Operators : https://youtu.be/oW_gTVciMrM
08 if and else : https://youtu.be/czK81ZOTyh8

What Is Functions in python and some example programs¶

In [3]:

def greeting():
    print("Please Subcribe")

In [4]:

greeting()

Please Subcribe

In [5]:

greeting()

Please Subcribe

In [6]:

def greeting():
    return "ramesh"

In [7]:

greeting()

Out[7]:

'ramesh'

In [8]:

def add_2num(a,b):
    sum = a+b
    return sum

In [9]:

add_2num(2,3)

Out[9]:

5

In [16]:

def add_2num(a,b):
    sum = a+b
    print('sum is:', sum)

In [17]:

add_2num(2,3)

sum is: 5

In [18]:

def greet(name):
    # """Greets a person by name."""
    print("Hello,", name + "!")

greet("Venkat")  # Outputs: Hello, Alice!

Hello, Venkat!

In [19]:

greet("vlr training")

Hello, vlr training!

In [20]:

def calculate_area(length, width):
    """Calculates the area of a rectangle."""
    area = length * width
    return area

result = calculate_area(5, 10)
print("The area is:", result)  # Outputs: The area is: 50

The area is: 50

In [22]:

def are_rect(le,wi):
    area = le*wi
    return area

In [23]:

are_rect(22,4)

Out[23]:

88

In [24]:

totalarea=are_rect(22,4)
print("area is",totalarea)

area is 88

In [29]:

def calculate_rectangle_area(length, width):
    """Calculates and returns the area of a rectangle."""
    area = length * width
    return area

def calculate_circle_area(radius):
    """Calculates and returns the area of a circle."""
    pi = 3.14159
    area = pi * radius * radius 
    return area

# Get user input 
shape = input("Enter shape (rectangle or circle): ")

if shape == "rectangle":
    length = float(input("Enter length: "))
    width = float(input("Enter width: "))
    area = calculate_rectangle_area(length, width)
    print("The area is:", area) 
elif shape == "circle":
    radius = float(input("Enter radius: "))
    area = calculate_circle_area(radius)
    print("The area is:", area) 
else:
    print("Invalid shape")

Enter shape (rectangle or circle): rectangle
Enter length: 44
Enter width: 3
The area is: 132.0

In [30]:

# student Grade with Function

In [32]:

def determine_grade(score):
    """Assigns a letter grade based on a numerical score."""
    if score >= 90:
        return "A"
    elif score >= 80:
        return "B"
    elif score >= 70:
        return "C"
    elif score >= 60:
        return "D"
    else:
        return "F"


student_name = input("Enter student name: ")
score = int(input("Enter score: "))

grade = determine_grade(score)
print(student_name, "earned a grade of", grade)

Enter student name: kumar 
Enter score: 99
kumar  earned a grade of A

In [39]:

def check_password(password):
    """Checks if a password meets complexity requirements."""
    has_upper = False
    has_lower = False
    has_digit = False

    for char in password:
        if char.isupper():
            has_upper = True
        if char.islower():
            has_lower = True
        if char.isdigit():
            has_digit = True

    if len(password) >= 8 and has_upper and has_lower and has_digit:
        return True
    else:
        return False

# Get password from the user
password = input("Enter a new password: ")

if check_password(password):
    print("Password is strong.")
else:
    print("Password is weak. Please follow complexity rules.")

Enter a new password: Ramsjds9
Password is strong.

In [ ]: