🌱 Beginner Level

python --version
# Output: Python 3.12.x

# Install via Homebrew (recommended)
brew install python3

# Check version
python3 --version

# Ubuntu/Debian
sudo apt update
sudo apt install python3 python3-pip

# Check version
python3 --version

# Example 1: Print simple text
print("Hello, World!")
print("Namaste World!")
print("I am learning Python!")

# Example 2: Print numbers
print(42)
print(3.14)
print(100 + 200)

# Example 3: Multiple values together
print("My age:", 20)
print("Sum:", 10 + 5, "and", "Diff:", 10 - 5)

# Example 4: Special characters
print("Line 1\nLine 2")     # \n = New line
print("Tab\there")           # \t = Tab space
print("He said \"Hello\"")   # \" = Quote inside string
print('It\'s Python!')       # \' = Apostrophe

# sep parameter — change separator
print("Python", "is", "awesome", sep="-")
# Output: Python-is-awesome

print("A", "B", "C", sep=" ❤️ ")
# Output: A ❤️ B ❤️ C

# end parameter — change line end
print("Hello", end=" ")
print("World!")
# Output: Hello World! (in same line)

# Single line comment — starts with #
print("Hello")  # This is also a comment, after code

"""
Multi-line comment (Docstring)
You can write comments
in multiple lines
"""

# Python ignores comments — they are only for our understanding!

# Creating variables — no special keyword needed!
name = "Himanshu"        # String (text)
age = 20                 # Integer (whole number)
height = 5.8             # Float (decimal number)
is_student = True        # Boolean (True/False)

print(name)       # Himanshu
print(age)        # 20
print(height)     # 5.8
print(is_student) # True

# type() function — check data type
print(type(42))         # <class 'int'>
print(type(3.14))       # <class 'float'>
print(type("Hello"))    # <class 'str'>
print(type(True))       # <class 'bool'>
print(type(None))       # <class 'NoneType'>

# Multiple assignment — multiple variables in one line!
a, b, c = 10, 20, 30
print(a, b, c)   # 10 20 30

# Same value to multiple variables
x = y = z = 100
print(x, y, z)   # 100 100 100

# Convert String to Integer
num_str = "42"
num_int = int(num_str)
print(num_int + 8)    # 50

# Integer to String
age = 20
msg = "I am " + str(age) + " years old"
print(msg)  # I am 20 years old

# Float conversions
print(int(3.7))       # 3 (decimal cut ho jaata hai)
print(float(5))       # 5.0
print(str(3.14))      # "3.14"

# Bool conversions
print(bool(0))        # False
print(bool(1))        # True
print(bool(""))       # False (empty string)
print(bool("Hello"))  # True (non-empty string)

# ✅ Valid names
my_name = "Himanshu"
age2 = 20
_private = "secret"
CONSTANT = 3.14

# ❌ Invalid names — ye ERROR denge!
# 2name = "wrong"      # Number se start nahi ho sakta
# my-name = "wrong"    # Hyphen allowed nahi
# my name = "wrong"    # Space allowed nahi
# class = "wrong"      # Reserved keyword nahi use kar sakte

# Basic input
name = input("Enter your name: ")
print("Hello,", name, "! Welcome to PyMaster!")

# Number input — convert using int() or float()
age = int(input("Enter your age: "))
print("You are", age, "years old!")

# Multiple values
num1 = float(input("First number: "))
num2 = float(input("Second number: "))
print("Sum =", num1 + num2)

name = "Himanshu"
age = 20
cgpa = 8.75

# f-string (Python 3.6+) — The Best Method!
print(f"My name is {name}")
print(f"Age: {age}, CGPA: {cgpa}")
print(f"After 5 years I will be {age + 5} years old!")
print(f"CGPA formatted: {cgpa:.1f}")  # 8.8 (1 decimal)

# You can also write expressions!
print(f"10 + 20 = {10 + 20}")
print(f"Name uppercase: {name.upper()}")

# Method 1: .format()
print("Name: {}, Age: {}".format("Himanshu", 20))
print("Name: {0}, Age: {1}".format("Himanshu", 20))

# Method 2: % formatting (old style)
print("Name: %s, Age: %d" % ("Himanshu", 20))

# Method 3: String concatenation
print("Name: " + "Himanshu" + ", Age: " + str(20))

a, b = 17, 5
print(f"Add: {a + b}")       # 22
print(f"Subtract: {a - b}")  # 12
print(f"Multiply: {a * b}")  # 85
print(f"Divide: {a / b}")    # 3.4  (float division)
print(f"Floor Div: {a // b}")# 3    (integer division)
print(f"Modulus: {a % b}")   # 2    (remainder)
print(f"Power: {a ** b}")    # 1419857  (17^5)

x, y = 10, 20
print(x == y)   # False — Equal?
print(x != y)   # True  — Not Equal?
print(x > y)    # False — Greater?
print(x < y)    # True  — Less than?
print(x >= 10)  # True  — Greater or equal?
print(x <= 5)   # False — Less or equal?

age = 20
has_id = True

# and — BOTH conditions must be true
print(age >= 18 and has_id)     # True

# or — ANY ONE condition must be true
print(age >= 21 or has_id)      # True

# not — Reverses the result
print(not has_id)               # False
print(not (age < 18))           # True

x = 10
x += 5    # x = x + 5 → 15
x -= 3    # x = x - 3 → 12
x *= 2    # x = x * 2 → 24
x /= 4    # x = x / 4 → 6.0
x //= 2   # x = x // 2 → 3.0
x **= 3   # x = x ** 3 → 27.0
print(x)  # 27.0

# Example 1: Simple if/else
age = 20
if age >= 18:
    print("You are an adult! ✅")
else:
    print("You are still a minor! ❌")

# Example 2: if/elif/else — Multiple conditions
marks = 85
if marks >= 90:
    print("Grade: A+ 🌟")
elif marks >= 80:
    print("Grade: A 🎉")
elif marks >= 70:
    print("Grade: B 👍")
elif marks >= 60:
    print("Grade: C 😊")
else:
    print("Grade: F 😢 — Work harder!")
# Output: Grade: A 🎉

# Example 3: Nested if
age = 25
has_license = True

if age >= 18:
    if has_license:
        print("You can drive! 🚗")
    else:
        print("Get a license first! 📝")
else:
    print("Wait until you turn 18! ⏳")

# Example 4: With logical operators
username = "admin"
password = "1234"

if username == "admin" and password == "1234":
    print("Login successful! ✅")
else:
    print("Wrong credentials! ❌")

# Example 5: Ternary operator (one-liner)
age = 20
status = "Adult" if age >= 18 else "Minor"
print(f"Status: {status}")  # Adult

# Example 1: With range()
for i in range(5):
    print(f"Count: {i}")
# 0, 1, 2, 3, 4

# Example 2: Iterate a list
fruits = ["Apple", "Banana", "Mango", "Orange"]
for fruit in fruits:
    print(f"I like {fruit}! 🍎")

# Example 3: range(start, stop, step)
for i in range(2, 11, 2):
    print(i, end=" ")  # 2 4 6 8 10

# Example 4: Iterate a string
for char in "Python":
    print(char, end="-")  # P-y-t-h-o-n-

# Example 1: Simple countdown
count = 5
while count > 0:
    print(f"⏳ {count}...")
    count -= 1
print("🚀 Launch!")

# Example 2: User input loop
while True:
    answer = input("Quit? (yes/no): ")
    if answer.lower() == "yes":
        print("Bye! 👋")
        break

# Example 3: Sum of numbers
total = 0
num = 1
while num <= 10:
    total += num
    num += 1
print(f"Sum of 1-10: {total}")  # 55

# break — Exit the loop
for i in range(10):
    if i == 5:
        break   # Stop at 5
    print(i)    # 0 1 2 3 4

# continue — Skip current iteration
for i in range(6):
    if i == 3:
        continue  # Skip 3
    print(i)      # 0 1 2 4 5

# pass — Do nothing (placeholder)
for i in range(3):
    pass  # Write code later

# Star Triangle Pattern
for i in range(1, 6):
    print("⭐" * i)
# ⭐
# ⭐⭐
# ⭐⭐⭐
# ⭐⭐⭐⭐
# ⭐⭐⭐⭐⭐

# Multiplication Table
num = 5
for i in range(1, 11):
    print(f"{num} x {i} = {num * i}")

# String Slicing — Extract parts
text = "Python Master"
print(text[0])      # P (first character)
print(text[-1])     # r (last character)
print(text[0:6])    # Python
print(text[7:])     # Master
print(text[::-1])   # retsaM nohtyP (reverse!)

# String Methods
msg = "  Hello Python World!  "
print(msg.strip())        # Remove spaces
print(msg.lower())        # all lowercase
print(msg.upper())        # ALL UPPERCASE
print(msg.title())        # Every Word Capital
print(msg.replace("Python", "Java"))
print(msg.split())        # Break into List
print("Python" in msg)    # True — check
print(msg.count("l"))     # 2 — how many times appeared
print(msg.find("Python")) # 8 — where found
print(msg.startswith(" ")) # True
print("-".join(["A","B","C"]))  # A-B-C