Conditional Statements: if

Execute code block 'a' if condition A is met, otherwise execute code block 'b'. This control flow is called a condisional statemant.

Basic Example

age = 20
if age >= 18:
    print("Adult")
else:
    print("Minor")

Multi-Condtiion Example

score = 75
if score >= 90:
    print("Excellent")
elif score >= 80:
    print("Good")
elif score >= 70:
    print("Average")
elif score >= 60:
    print("Pass")
else:
    print("Fail")

Truthy/Falsy Values

In Python, values evaluate to:

• False: None, empty lists/sets/dicts/tuples/strings, 0, False
• True: Non-empty sequences, non-zero numbers, True

value = 1
if value:
    print("Valid")

Compound Conditions

# AND condition
if condition_a and condition_b:
    pass

# OR condition
if condition_a or condition_b:
    pass

# NOT condition
if not condition_a:
    pass

Loop Statements: for

Iterates over sequence items like lists or strings.

Basic Iteration

phones = ["Apple", "Huawei", "Xiaomi"]
for phone in phones:
    print(f"Current phone: {phone}")

Indexed Iteration

for index, phone in enumerate(phones):
    print(f"Phone {index + 1}: {phone}")

Loop Control

# Break example
for i in [0, 1, 2]:
    if i == 1:
        break
    print(i)

# Continue example
for i in [0, 1, 2]:
    if i == 1:
        continue
    print(i)

For-Else Structure

for i in [0, 1, 2]:
    if i == 1:
        continue
    print(i)
else:
    print("Loop completed normally")

Loop Statements: while

Repeats execution while condition remains true.

Basic While Loop

age = 1
while age <= 3:
    print(f"Age {age}: Not ready for school")
    age += 1
print("Ready for kindergarten")

Infinite Loop

while True:
    # Requires break condition
    pass

While-Else Structure

age = 1
while age <= 3:
    print(f"Current age: {age}")
    age += 1
else:
    print("Ready for school")