Python for Beginners| Documentation

Python Course Code Examples

This is a Documentation of the python code i used and created , for learning python. Its easy to understand and Learn.Feel free to learn from here. For more advanced concepts, please refer to the github repo at https://github.com/iamdipsan/Python-for-cybersecurity

First Program
Variables and Data Types
Strings
Numbers
Getting Input from Users
Building a Basic Calculator
First Madlibs
Lists
List Functions
Tuples
Functions
Return Statement
If Statements
If Comparisons
Guessing Game 2
For Loop
Exponential Function
2D List and For Loops

First Program

This program is use to show how print() command works.

# This is a simple "Hello World" program that demonstrates basic print statements

# Print the string "Hello world" to the console
print("Hello world")

# Print the integer 1 to the console
print(1)

# Print the integer 20 to the console
print(20)

Variables and Data Types

A variable in Python is a reserved memory location to store values. Data types define the type of data a variable can hold ie integer,float, string etc.

# This program demonstrates the use of variables and string concatenation

# Assign the string "Dipsan" to the variable _name
_name = "Dipsan"

# Assign the integer 20 to the variable _age
_age = 20

# Assign the string "piano" to the variable _instrument
_instrument = "piano"

# Print a sentence using string concatenation with the _name variable
print("my name is" + _name + ".")

# Print a sentence using string concatenation, converting _age to a string
print("I'm" + str(_age) + "years old")  # Converting int to string for concatenation

# Print a simple string
print("i dont like hanging out")

# Print a sentence using string concatenation with the _instrument variable
print("i love " + _instrument + ".")

Strings

Sequences of characters used to store and manipulate text. They are created by enclosing text in single quotes ('Hello'), double quotes ("Hello"), or triple quotes for multi-line strings ('''Hello'''). Example: "Hello, World!".

# This script demonstrates various string operations

# Assign a string to the variable 'phrase'
phrase = "DipsansAcademy"

# Print a simple string
print("This is a string")

# Concatenate strings and print the result
print('This' + phrase + "")

# Convert the phrase to uppercase and print
print(phrase.upper())

# Convert the phrase to lowercase and print
print(phrase.lower())

# Check if the uppercase version of phrase is all uppercase and print the result
print(phrase.upper().isupper())

# Print the length of the phrase
print(len(phrase))

# Print the first character of the phrase (index 0)
print(phrase[0])

# Print the second character of the phrase (index 1)
print(phrase[1])

# Print the fifth character of the phrase (index 4)
print(phrase[4])

# Find and print the index of 'A' in the phrase
print(phrase.index("A"))

# Replace "Dipsans" with "kadariya" in the phrase and print the result
print(phrase.replace("Dipsans", "kadariya"))

Numbers

Numbers are used for various numeric operations and math functions:

# Import all functions from the math module
from math import *  # Importing math module for additional math functions

# This script demonstrates various numeric operations and math functions

# Print the integer 20
print(20)

# Multiply 20 by 4 and print the result
print(20 * 4)

# Add 20 and 4 and print the result
print(20 + 4)

# Subtract 4 from 20 and print the result
print(20 - 4)

# Perform a more complex calculation and print the result
print(3 + (4 - 5))

# Calculate the remainder of 10 divided by 3 and print the result
print(10 % 3)

# Assign the value 100 to the variable _num
_num = 100

# Print the value of _num
print(_num)

# Convert _num to a string, concatenate with other strings, and print
print(str(_num) + " is my fav number")  # Converting int to string for concatenation

# Assign -10 to the variable new_num
new_num = -10

# Print the absolute value of new_num
print(abs(new_num))  # Absolute value

# Calculate 3 to the power of 2 and print the result
print(pow(3, 2))     # Power function

# Find the maximum of 2 and 3 and print the result
print(max(2, 3))     # Maximum

# Find the minimum of 2 and 3 and print the result
print(min(2, 3))     # Minimum

# Round 3.2 to the nearest integer and print the result
print(round(3.2))    # Rounding

# Round 3.7 to the nearest integer and print the result
print(round(3.7))

# Calculate the floor of 3.7 and print the result
print(floor(3.7))    # Floor function

# Calculate the ceiling of 3.7 and print the result
print(ceil(3.7))     # Ceiling function

# Calculate the square root of 36 and print the result
print(sqrt(36))      # Square root

Getting Input from Users

This program is used to show how to use the input() function to get user input:

# This script demonstrates how to get user input and use it in string concatenation

# Prompt the user to enter their name and store it in the 'name' variable
name = input("Enter your name : ")

# Prompt the user to enter their age and store it in the 'age' variable
age = input("Enter your age. : ")

# Print a greeting using the user's input, concatenating strings
print("hello " + name + " Youre age is " + age + " .")

Building a Basic Calculator

This program creates a simple calculator that adds two numbers:

# This script creates a basic calculator that adds two numbers

# Prompt the user to enter the first number and store it in 'num1'
num1 = input("Enter first number : ")

# Prompt the user to enter the second number and store it in 'num2'
num2 = input("Enter second number: ")

# Convert the input strings to integers and add them, storing the result
result = int(num1) + int(num2)

# Print the result of the addition
print(result)

First Madlibs

This program creates a simple Mad Libs game:

# This program is used to create a simple Mad Libs game.

# Prompt the user to enter an adjective and store it in 'adjective1'
adjective1 = input("Enter an adjective: ")

# Prompt the user to enter an animal and store it in 'animal'
animal = input("Enter an animal: ")

# Prompt the user to enter a verb and store it in 'verb'
verb = input("Enter a verb: ")

# Prompt the user to enter another adjective and store it in 'adjective2'
adjective2 = input("Enter another adjective: ")

# Print the first sentence of the Mad Libs story using string concatenation
print("I have a " + adjective1 + " " + animal + ".")

# Print the second sentence of the Mad Libs story
print("It likes to " + verb + " all day.")

# Print the third sentence of the Mad Libs story
print("My " + animal + " is so " + adjective2 + ".")

Lists

A list is a collection of items in Python that is ordered and changeable. Each item (or element) in a list has an index, starting from 0. Lists can contain items of different data types (like integers, strings, or even other lists). A list is defined using square brackets [], with each item separated by a comma.

# This script demonstrates basic list operations

# Create a list of friends' names
friends = ["Roi", "alex", "jimmy", "joseph"]

# Print the entire list
print(friends)

# Print the first element of the list (index 0)
print(friends[0])

# Print the second element of the list (index 1)
print(friends[1])

# Print the third element of the list (index 2)
print(friends[2])

# Print the fourth element of the list (index 3)
print(friends[3])

# Print the last element of the list using negative indexing
print(friends[-1])

# Print a slice of the list from the second element to the end
print(friends[1:])

# Print a slice of the list from the second element to the third (exclusive)
print(friends[1:3])

# Change the second element of the list to "kim"
friends[1] = "kim"

# Print the modified list
print(friends)

List Functions

This script showcases various list methods:

# This script demonstrates various list functions and methods

# Create a list of numbers
numbers = [4, 6, 88, 3, 0, 34]

# Create a list of friends' names
friends = ["Roi", "alex", "jimmy", "joseph", "kevin", "tony", "jimmy"]

# Print both lists
print(numbers)
print(friends)

# Add all elements from 'numbers' to the end of 'friends'
friends.extend(numbers)

# Add "hulk" to the end of the 'friends' list
friends.append("hulk")

# Insert "mikey" at index 1 in the 'friends' list
friends.insert(1, "mikey")

# Remove the first occurrence of "Roi" from the 'friends' list
friends.remove("Roi")

# Print the index of "mikey" in the 'friends' list
print(friends.index("mikey"))

# Remove and print the last item in the 'friends' list
print(friends.pop())

# Print the current state of the 'friends' list
print(friends)

# Remove all elements from the 'friends' list
friends.clear()

# Print the empty 'friends' list
print(friends)

# Sort the 'numbers' list in ascending order
numbers.sort()

# Print the sorted 'numbers' list
print(numbers)

Tuples

A tuple is a collection of items in Python that is ordered but unchangeable (immutable). Once you create a tuple, you cannot add, remove, or change its elements. Like lists, tuples can contain items of different data types. A tuple is defined using parentheses (), with each item separated by a comma.

# This script introduces tuples and their immutability

# Create a tuple with two elements
values = (3, 4)

# Print the entire tuple
print(values)

# Print the second element of the tuple (index 1)
print(values[1])

# The following line would cause an IndexError if uncommented:
# print(values[2])  # This would cause an IndexError

# The following line would cause a TypeError if uncommented:
# values[1] = 30    # This would cause a TypeError as tuples are immutable

# The following line would print the modified tuple if the previous line worked:
# print(values)

Functions

A function is a block of reusable code that performs a specific task. Functions can take inputs (called arguments), process them, and return an output. Functions help organize code, make it more modular, and avoid repetition. n Python, a function is defined using the def keyword, followed by the function name, parentheses (), and a colon :. The code inside the function is indented. This code demonstrates how to define and call functions:

# This script demonstrates how to define and call functions

# Define a function called 'greetings' that prints two lines
def greetings():
    print("HI, Welcome to programming world of python")
    print("keep learning")

# Print a statement before calling the function
print("this is first statement")

# Call the 'greetings' function
greetings()

# Print a statement after calling the function
print("this is last statement")

# Define a function 'add' that takes two parameters and prints their sum
def add(num1, num2):
    print(int(num1) + int(num2))

# Call the 'add' function with arguments 3 and 4
add(3, 4)

Return Statement

he return statement is used in a function to send back (or "return") a value to the caller. When return is executed, it ends the function, and the value specified after return is sent back to where the function was called.

This program shows how to use the return statement in functions:

# This script demonstrates the use of return statements in functions

# Define a function 'square' that returns the square of a number
def square(num):
    return num * num
    # Any code after the return statement won't execute

# Call the 'square' function with argument 2 and print the result
print(square(2))

# Call the 'square' function with argument 4 and print the result
print(square(4))

# Call the 'square' function with argument 3, store the result, then print it
result = square(3)
print(result)

If Statements

The if statement evaluates a condition (an expression that returns True or False). If the condition is True, the block of code under the if statement is executed. elif : Short for "else if," it allows you to check multiple conditions. It is used when you have multiple conditions to evaluate, and you want to execute a block of code for the first True condition. else: The else statement runs a block of code if none of the preceding if or elif conditions are True.

# This script demonstrates the use of if-elif-else statements

# Set boolean variables for conditions
is_boy = True
is_handsome = False

# Check conditions using if-elif-else statements
if is_boy and is_handsome:
    print("you are a boy & youre handsome")
    print("hehe")
elif is_boy and not (is_handsome):
    print("Youre a boy but sorry not handsome")
else:
    print("youre not a boy")

If Comparisons

This code demonstrates comparison operations in if statements:

# This script demonstrates comparison operations in if statements

# Define a function to find the maximum of three numbers
def max_numbers(num1, num2, num3):
    if num1 >= num2 and num1 >= num3:
        return num1
    elif num2 >= num1 and num2 >= num3:
        return num2
    else:
        return num3

# Test the max_numbers function with different inputs
print(max_numbers(20, 40, 60))
print(max_numbers(30, 14, 20))
print(max_numbers(3, 90, 10))

print("For min_number")

# Define a function to find the minimum of three numbers
def min_numbers(num1, num2, num3):
    if num1 <= num2 and num1 <= num3:
        return num1
    elif num2 <= num1 and num2 <= num3:
        return num2
    else:
        return num3

# Test the min_numbers function with different inputs
print(min_numbers(20, 40, 60))
print(min_numbers(30, 14, 20))
print(min_numbers(3, 90, 10))

Guessing Game 2

This script improves the guessing game with more features:

# This script improves the guessing game with more features

import random

# Generate a random number between 1 and 20
secret_number = random.randint(1, 20)

# Initialize the number of attempts and set a limit
attempts = 0
attempt_limit = 5

# Loop to allow the user to guess the number
while attempts < attempt_limit:
    guess = int(input(f"Guess the number (between 1 and 20). You have {attempt_limit - attempts} attempts left: "))
    if guess == secret_number:
        print("Congratulations! You guessed the number!")
        break
    elif guess < secret_number:
        print("Too low!")
    else:
        print("Too high!")
    attempts += 1

# If the user does not guess correctly within the attempt limit, reveal the number
if guess != secret_number:
    print(f"Sorry, the correct number was {secret_number}.")

For Loop

A for loop is used to iterate over a sequence of elements, such as a list, tuple, string, or range. This code introduces the for loop:

# List of numbers
numbers = [1, 2, 3, 4, 5]

# Iterate over each number in the list
for number in numbers:
    # Print the current number
    print(number)

# Output:
# 1
# 2



# 3
# 4
# 5

# List of friends
friends = ["Roi", "alex", "jimmy", "joseph", "kevin", "tony", "jimmy"]

# Iterate over each friend in the list
for friend in friends:
    # Print the name of the current friend
    print(friend)

# Output:
# Roi
# alex
# jimmy
# joseph
# kevin
# tony
# jimmy

# Use range to generate numbers from 0 to 4
for num in range(5):
    print(num)

# Output:
# 0
# 1
# 2
# 3
# 4

Exponential Function

Exponential functions are mathematical functions where a constant base is raised to a variable exponent. This script shows how to use the math.pow function:

# This script demonstrates the use of the exponential function
def exponentialFunction(base,power):
    result = 1
    for index in range(power):
        result = result * base
    return result

print(exponentialFunction(3,2))
print(exponentialFunction(4,2))
print(exponentialFunction(5,2))

#or you can power just by
print(2**3) #number *** power

2D List and For Loops

A 2D list (or 2D array) in Python is essentially a list of lists, where each sublist represents a row of the matrix. You can use nested for loops to iterate over elements in a 2D list. Here’s how you can work with 2D lists and for loops:

# This script demonstrates the use of 2D List and For Loops
# Define a 2D list (list of lists)
num_grid = [
    [1, 2, 3],  # Row 0: contains 1, 2, 3
    [4, 5, 6],  # Row 1: contains 4, 5, 6
    [7, 8, 9],  # Row 2: contains 7, 8, 9
    [0]         # Row 3: contains a single value 0
]

# Print specific elements in num_grid
print(num_grid[0][0])   # Print value in the zeroth row, zeroth column (value: 1)
print(num_grid[1][0])   # Print value in the first row, zeroth column (value: 4)
print(num_grid[2][2])   # Print value in the second row, second column (value: 9)


print("using nested for loops")
for row in num_grid :
   for col in row:
    print(col)

This is how we can use 2D List and For Loops.

The reference material for this blog was from Mike form FreeCodeCamp.org. Thank you.