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Loop & Control Comparisons 🚀

Mentor's Note: Choosing the wrong loop won't always crash your program, but it will make your code harder to read and slower to run. Let's learn to pick the right tool for the job! 💡


1. For Loop vs. While Loop 🥊

Imagine you are filling a bucket with water.

  • Scenario A (FOR): You have exactly 5 small cups of water. You pour all 5. 📦
  • Scenario B (WHILE): You hold the bucket under a tap. You keep it there UNTIL the bucket is full. 📦
Feature For Loop While Loop
Logic "For every item in this collection..." "As long as this is true..."
End Point Pre-determined (fixed count). Dynamic (depends on a condition).
Risk Safe. Low risk of infinite loops. Higher risk of Infinite Loops 🛑.
Setup Easy (built-in range). Requires manual initialization and update.

When to pick?

  • Use FOR when you know the number of iterations (e.g., "Loop 10 times" or "Loop over this list").
  • Use WHILE when you don't know the count (e.g., "Wait for user to type 'exit'").

2. Break vs. Continue 🥊

Imagine you are reading a book.

  • BREAK: You find a page that is torn. You close the book and stop reading entirely. 🛑
  • CONTINUE: You find a page that is a boring advertisement. You skip that page and immediately move to the next chapter. ⏭️
Feature Break Continue
Scope Terminates the entire loop. Terminates the current turn only.
Next Action Runs the code AFTER the loop. Runs the NEXT turn of the loop.

🎨 Visual Logic: The Selection Flow

graph TD
    A[Need to Repeat Code?] --> B{Know the Count?}
    B -- Yes --> C[Use FOR Loop ✅]
    B -- No --> D[Use WHILE Loop ✅]

    E[Inside the Loop] --> F{Found what you need?}
    F -- Yes --> G[Use BREAK to exit 🛑]
    F -- No, skip this one --> H[Use CONTINUE ⏭️]

💻 Implementation: Comparison Lab

# 🛒 Scenario: Searching for a user in a list
users = ["Ankit", "Vishnu", "John", "Doe"]

for u in users:
    if u == "Vishnu":
        print("Found him! Stopping search. 🛑")
        break
# 🛒 Scenario: Waiting for a specific input
command = ""
while command != "exit":
    command = input("Type 'exit' to stop: ⌨️")

📊 Sample Dry Run

Loop Type Turn Condition Action
For 1 of 5 True Run logic
While Unknown Checks every turn Run logic

💡 Interview Tip 👔

"Interviewers often ask how to simulate a do-while loop in Python. Answer: Use a while True: loop with a break condition at the end of the block!"


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