🔄 Programming Loops Cheat Sheet

📋 Quick Reference

For Loop Syntax

Python

for item in sequence:
    # code block

Java

for (initialization; condition; increment) {
    // code block
}

C

for (initialization; condition; increment) {
    // code block
}

JavaScript

for (initialization; condition; increment) {
    // code block
}

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While Loop Syntax

Python

while condition:
    # code block

Java

while (condition) {
    // code block
}

C

while (condition) {
    // code block
}

JavaScript

while (condition) {
    // code block
}

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Do-While Loop Syntax

Java

do {
    // code block
} while (condition);

C

do {
    // code block
} while (condition);

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🎯 Common Patterns

Counting 1 to N

for i in range(1, n + 1):
    print(i)

Sum of Numbers

total = 0
for num in numbers:
    total += num

Factorial

factorial = 1
for i in range(1, n + 1):
    factorial *= i

Reverse Number

reverse = 0
while num > 0:
    reverse = reverse * 10 + num % 10
    num //= 10

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⚡ Control Statements

Break Statement

for i in range(10):
    if i == 5:
        break  # Exit loop
    print(i)

Continue Statement

for i in range(10):
    if i % 2 == 0:
        continue  # Skip iteration
    print(i)

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🎪 Nested Loops

Pattern Printing

for i in range(n):
    for j in range(i + 1):
        print("*", end="")
    print()

Matrix Operations

for i in range(rows):
    for j in range(cols):
        # Process matrix[i][j]
        pass

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📊 Performance Tips

Optimization Guidelines

• ✅ Use range() instead of list creation
• ✅ Minimize operations inside loops
• ✅ Consider list comprehensions for simple operations
• ✅ Use appropriate loop types for the task

Common Pitfalls

• ❌ Infinite loops (missing condition update)
• ❌ Off-by-one errors in loop bounds
• ❌ Modifying collection while iterating
• ❌ Unnecessary nested loops

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🔍 Debugging Checklist

• Loop condition is correct
• Loop variables are initialized
• Loop body updates condition
• No infinite loops
• Correct loop bounds
• Proper indentation

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Last updated: Phase 3 Implementation