🔋 Generators

# Normal function — sab ek saath memory mein
def make_list(n):
    result = []
    for i in range(n):
        result.append(i**2)
    return result

# Generator — ek ek karke deta hai
def gen_squares(n):
    for i in range(n):
        yield i**2  # yield se generator banta hai

g = gen_squares(5)
for val in g:
    print(val, end=" ")  # 0 1 4 9 16

def counter(start, end):
    while start <= end:
        yield start
        start += 1

c = counter(1, 5)
print(next(c))  # 1
print(next(c))  # 2
print(next(c))  # 3

# Baaki sab ek saath
for val in c:
    print(val, end=" ")  # 4 5

# List comprehension — [] — memory mein sab
lst = [x**2 for x in range(10)]

# Generator expression — () — lazy
gen = (x**2 for x in range(10))

print(sum(gen))   # 285

# Infinite generator!
def infinite():
    n = 0
    while True:
        yield n
        n += 1

g = infinite()
print(next(g))  # 0
print(next(g))  # 1

# Chapter 18: Generators — Advanced Practice
print("=== Generators Practice ===")

# Example 1: Basic usage
result = "Python mein Generators bahut powerful hai!"
print(result)

# Example 2: Real world use
data = ["Generators", "Python", "Hindi", "PythonHindi.in"]
for item in data:
    print(f"Item: {item}")

print("\nPractice complete! Great job! 🎉")

# Chapter 18: Generators — Advanced Examples
# Yeh code copy karo aur run karo!

# Example 1: Basic concept
print("=== Chapter 18: Generators ===")

# Example 2: List operations
items = ["Python", "Hindi", "Code", "Practice"]
for i, item in enumerate(items, 1):
    print(f"{i}. {item}")

# Example 3: Dictionary usage
chapter_info = {
    "number": 18,
    "title":  "Generators",
    "level":  "Intermediate",
    "done":   False
}
for key, value in chapter_info.items():
    print(f"  {key:10}: {value}")

# Example 4: Function
def practice_summary(chapter, completed=False):
    status = "Complete ✅" if completed else "In Progress ⏳"
    return f"Chapter {chapter}: {status}"

print(practice_summary(18))
print(practice_summary(18, True))