Control Flow

If statements, loops, and controlling program flow with conditions.

If Statements

Execute code based on conditions.
Use if, elif (else if), and else.
Indentation defines the code block.

age = 18

if age < 13:
    print("Child")
elif age < 18:
    print("Teenager")
else:
    print("Adult")

# Nested if
score = 85
if score >= 60:
    if score >= 90:
        print("A grade")
    else:
        print("B grade")

For Loops

Iterate over sequences (lists, strings, ranges).
Use range() for numeric loops.
Access index with enumerate().

# Loop through range
for i in range(5):
    print(i)  # 0, 1, 2, 3, 4

# Loop through list
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit)

# With index
for index, fruit in enumerate(fruits):
    print(f"{index}: {fruit}")

While Loops

Repeat while condition is True.
Be careful to avoid infinite loops.
Use break to exit loop early.

# Basic while loop
count = 0
while count < 5:
    print(count)
    count += 1

# With break
while True:
    user_input = input("Enter 'quit' to exit: ")
    if user_input == "quit":
        break
    print(f"You entered: {user_input}")

Loop Control

break: Exit loop immediately
continue: Skip to next iteration
pass: Do nothing (placeholder)

# break example
for i in range(10):
    if i == 5:
        break
    print(i)  # 0, 1, 2, 3, 4

# continue example
for i in range(5):
    if i == 2:
        continue
    print(i)  # 0, 1, 3, 4

# pass example
for i in range(3):
    pass  # TODO: implement later