Python Control Structures Cheat Sheet

Conditional Statements

if Statement

if condition:
    # code block

if-else Statement

if condition:
    # code block if condition is true
else:
    # code block if condition is false

if-elif-else Statement

if condition1:
    # code block if condition1 is true
elif condition2:
    # code block if condition2 is true
else:
    # code block if none of the conditions are true

Nested if Statements

if condition1:
    if condition2:
        # code block if both condition1 and condition2 are true

Exception Handling

try-except Block

try:
    # code block that may raise an exception
    result = 10 / 0
except ZeroDivisionError:
    # code block to handle the exception
    print("Cannot divide by zero!")

try-except-else Block

try:
    result = 10 / 2
except ZeroDivisionError:
    print("Cannot divide by zero!")
else:
    print("Division successful:", result)
# Output: Division successful: 5.0

try-except-finally Block

try:
    result = 10 / 2
except ZeroDivisionError:
    print("Cannot divide by zero!")
finally:
    print("This will always execute.")
# Output: Division successful: 5.0
# Output: This will always execute.

Miscellaneous

ternary Conditional Operator

x = 10
y = 20
max_value = x if x > y else y
print(max_value)
# Output: 20

while-else Statement

i = 0
while i < 5:
    print(i)
    i += 1
else:
    print("Loop is done")
# Output: 0 1 2 3 4
# Output: Loop is done

for-else Statement

for i in range(5):
    print(i)
else:
    print("Loop is done")
# Output: 0 1 2 3 4
# Output: Loop is done

Looping Statements

for Loop

for variable in iterable:
    # code block

Example of for Loop

for i in range(5):
    print(i)
# Output: 0 1 2 3 4

while Loop

while condition:
    # code block

Example of for Loop

for i in range(5):
    print(i)
# Output: 0 1 2 3 4

Nested Loops

for i in range(3):
    for j in range(3):
        print(i, j)

Loop Control Statements

break Statement

for i in range(5):
    if i == 3:
        break
    print(i)
# Output: 0 1 2

continue Statement

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

pass Statement

for i in range(5):
    if i == 3:
        pass
    print(i)
# Output: 0 1 2 3 4

Comprehensions

List Comprehension

squares = [x**2 for x in range(10)]
print(squares)
# Output: [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

Dictionary Comprehension

squares = {x: x**2 for x in range(10)}
print(squares)
# Output: {0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81}

Set Comprehension

squares = {x**2 for x in range(10)}
print(squares)
# Output: {0, 1, 64, 4, 36, 9, 16, 81, 49, 25}

Generator Comprehension

squares = (x**2 for x in range(10))
for square in squares:
    print(square)
# Output: 0 1 4 9 16 25 36 49 64 81