Loop Control Statements

Beginner ~15 min read

Loop control statements give you fine-grained control over loop execution. break exits the loop entirely, continue skips to the next iteration, and pass does nothing (but is syntactically useful).

Statement	Effect	Common Use
`break`	Exit loop immediately	Found what you're looking for
`continue`	Skip to next iteration	Filter/skip certain items
`pass`	Do nothing	Placeholder for future code

The `break` Statement

Use break to exit a loop immediately. Execution continues with the first statement after the loop. If the loop has an else clause, it is NOT executed.

Output

Click Run to execute your code

Performance Tip: Using break for early exit can significantly improve performance. When searching a million items for a value that's at position 42, break lets you stop after checking just 42 items instead of all million!

The `continue` Statement

Use continue to skip the rest of the current iteration and move to the next one. The loop doesn't end - it just skips ahead.

# The continue Statement - Skip Current Iteration

# Skip even numbers
print("=== Skip Even Numbers ===")
for i in range(1, 11):
    if i % 2 == 0:
        continue  # Skip to next iteration
    print(i)  # Only prints odd numbers

print()

# Skip specific items
print("=== Skip Specific Items ===")
fruits = ["apple", "banana", "cherry", "date", "elderberry"]
skip = "cherry"

for fruit in fruits:
    if fruit == skip:
        print(f"(skipping {skip})")
        continue
    print(f"Processing: {fruit}")

print()

# Filter while processing
print("=== Filter Invalid Data ===")
data = [10, -5, 20, None, 30, "", 40]

total = 0
valid_count = 0

for item in data:
    # Skip invalid data
    if item is None or item == "" or (isinstance(item, int) and item < 0):
        print(f"Skipping invalid: {item}")
        continue

total += item
    valid_count += 1
    print(f"Added {item}, running total: {total}")

print(f"Total: {total}, Valid items: {valid_count}")

print()

# Continue in while loop
print("=== Continue in While Loop ===")
i = 0
while i < 5:
    i += 1
    if i == 3:
        print("(skipping 3)")
        continue
    print(f"i = {i}")

Output

Click Run to execute your code

Pro Tip: continue is great for "guard clauses" at the start of a loop. Check for invalid conditions and continue early, then write the main logic without deep nesting.

The `pass` Statement

The pass statement does nothing. It's a placeholder when Python syntax requires a statement but you don't want to execute any code.

# The pass Statement - Do Nothing Placeholder

# Pass as placeholder in empty loop
print("=== Pass as Placeholder ===")

# When you need a loop but haven't written the code yet
for i in range(3):
    pass  # TODO: implement later
print("Loop completed (did nothing)")

print()

# Pass in conditional
print("=== Pass in Conditional ===")
for i in range(5):
    if i == 2:
        pass  # Intentionally do nothing for 2
        print(f"  (pass executed for {i})")
    else:
        print(f"Processing {i}")

print()

# Pass vs continue - they're different!
print("=== Pass vs Continue ===")
print("With pass:")
for i in range(3):
    if i == 1:
        pass
    print(f"  i = {i}")  # ALL values print

print("\nWith continue:")
for i in range(3):
    if i == 1:
        continue
    print(f"  i = {i}")  # 1 is skipped!

print()

# Common use: Empty class or function
print("=== Pass in Definitions ===")
print("""
# Empty class placeholder
class MyClass:
    pass

# Empty function placeholder
def my_function():
    pass

# Empty conditional branch
if condition:
    do_something()
else:
    pass  # Nothing to do in else case
""")

Output

Click Run to execute your code

Don't Confuse pass and continue! pass does nothing and continues to the next line. continue skips the rest of the iteration. After pass, the code keeps running; after continue, it jumps to the next iteration.

Practical Examples

These statements are essential for real-world patterns like validation, filtering, and early-exit optimizations.

# Practical Loop Control Examples

# 1. Input validation with retry limit
print("=== Retry with Limit ===")
valid_passwords = ["secret", "admin123"]
inputs = ["wrong", "bad", "secret"]  # Simulated inputs
max_attempts = 5

for attempt in range(1, max_attempts + 1):
    password = inputs[attempt - 1] if attempt <= len(inputs) else "none"
    print(f"Attempt {attempt}: trying '{password}'")

if password in valid_passwords:
        print("Access granted!")
        break
else:
    print("Too many failed attempts. Locked out!")

print()

# 2. Processing with filters
print("=== Process Valid Data Only ===")
transactions = [
    {"id": 1, "amount": 100, "status": "completed"},
    {"id": 2, "amount": -50, "status": "pending"},
    {"id": 3, "amount": 200, "status": "completed"},
    {"id": 4, "amount": 75, "status": "failed"},
    {"id": 5, "amount": 150, "status": "completed"},
]

total = 0
for tx in transactions:
    # Skip invalid transactions
    if tx["status"] != "completed":
        print(f"Skipping tx {tx['id']} (status: {tx['status']})")
        continue
    if tx["amount"] < 0:
        print(f"Skipping tx {tx['id']} (negative amount)")
        continue

total += tx["amount"]
    print(f"Processing tx {tx['id']}: +${tx['amount']}")

print(f"Total processed: ${total}")

print()

# 3. Early exit optimization
print("=== Early Exit for Performance ===")
big_list = list(range(1, 1000001))  # 1 to 1,000,000
target = 42

for i, num in enumerate(big_list):
    if num == target:
        print(f"Found {target} at index {i}")
        print(f"(Only checked {i + 1} items instead of {len(big_list)})")
        break

Output

Click Run to execute your code

Common Mistakes

1. Using break when you meant continue

# Wrong - exits the entire loop!
for item in items:
    if not is_valid(item):
        break  # Stops processing all items!

# Correct - skip invalid, process rest
for item in items:
    if not is_valid(item):
        continue  # Skip this item, continue with others

2. Confusing pass with continue

# These are different!
for i in range(3):
    if i == 1:
        pass
    print(i)  # Prints 0, 1, 2 - pass does nothing

for i in range(3):
    if i == 1:
        continue
    print(i)  # Prints 0, 2 - continue skips 1

3. Forgetting break only exits ONE loop

# break only exits the inner loop!
for i in range(3):
    for j in range(3):
        if j == 1:
            break  # Only breaks inner loop
    print(f"i={i}")  # Still runs for each i!

4. Unnecessary else after continue

# Unnecessary else
for num in numbers:
    if num % 2 == 0:
        continue
    else:  # This else is redundant!
        print(num)

# Cleaner
for num in numbers:
    if num % 2 == 0:
        continue
    print(num)  # Only reaches here if didn't continue

Exercise: Find First Even Number

Task: Find the first even number in a list.

Requirements:

Iterate through the list
Skip odd numbers with continue
Print and break when even number found

Output

Click Run to execute your code

Show Solution

numbers = [1, 3, 5, 7, 8, 9, 10]
found_even = None

for num in numbers:
    if num % 2 != 0:  # Odd number
        continue  # Skip to next
    # If we reach here, it's even
    found_even = num
    print(f"First even: {num}")
    break

if found_even is None:
    print("No even numbers found")

Summary

break: Exit the loop immediately, skip loop's else
continue: Skip rest of current iteration, go to next
pass: Do nothing (placeholder)
break in nested loops: Only exits the innermost loop
Use break for early exit (found item, reached limit)
Use continue for filtering/skipping invalid items

What's Next?

Now that you can control loop flow, let's learn about nested loops - loops inside loops! These are essential for working with 2D data like grids, matrices, and combinations.

Previous While Loops

Next Nested Loops

The break Statement

The continue Statement

The pass Statement

Practical Examples

Common Mistakes

1. Using break when you meant continue

2. Confusing pass with continue

3. Forgetting break only exits ONE loop

4. Unnecessary else after continue

Exercise: Find First Even Number

Summary

What's Next?

Enjoying these tutorials?

The `break` Statement

The `continue` Statement

The `pass` Statement