Difference Between for And while Loop

Python Loop Guide: for vs while Loop Explained with Examples

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1. 🤔 Basic Difference

for loop is used when the number of iterations is known, while while loop is used when the number of iterations is unknown and depends on a condition.

Feature	for loop	while loop
Usage	Used to iterate over a sequence	Used to repeat while a condition is True
Iteration Count	Known or fixed	Unknown or based on condition
Risk of Infinite Loop	Low	High (if condition never becomes False)

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2. 🔁 Syntax

for Loop Syntax

for item in sequence:
    # do something

while Loop Syntax

while condition:
    # do something

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3. 🧪 Example: Print numbers from 1 to 5

Using for loop:

for i in range(1, 6):
    print(i)

Using while loop:

i = 1
while i <= 5:
    print(i)
    i += 1

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4. 🍎 Looping Through a List

Using for loop:

fruits = ['apple', 'banana', 'mango']
for fruit in fruits:
    print(fruit)

Using while loop:

fruits = ['apple', 'banana', 'mango']
i = 0
while i < len(fruits):
    print(fruits[i])
    i += 1

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5. ⚠️ Infinite Loop Danger

Important: A while loop can run forever if the condition never becomes False.

Example of Infinite while loop:

i = 1
while i > 0:
    print(i)
    # i is never decreased or changed

Note: Always ensure the loop has an exit condition!

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6. ✅ When to Use What?

• Use for when iterating over a sequence like a list, tuple, or range.
• Use while when looping based on a condition or waiting for an event.

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7. 🧾 Summary Table

Aspect	for loop	while loop
Best for	Known number of iterations	Unknown number of iterations
Initialization	Done by range() or sequence	Manually before loop
Loop Control	Automatic	Manual (update variable inside loop)
Readability	Cleaner for fixed loops	Better for condition-based repetition

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📌 Final Tip

Use for loop when you know how many times to run.
Use while loop when you're not sure and the loop depends on some condition (like user input or sensor reading).

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Hope this helps you understand Python loops better! 🚀

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📚 Practice Questions:

• ➤ Exercises

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📚 Related Topics:

• ➤ Python Arithmetic Operators
• ➤ Basic String Functions
• ➤ Advanced String Functions
• ➤ Basic List Functions
• ➤ Advanced List Functions : Part-1
• ➤ Advanced List Functions : Part-2
• ➤ Basic Tuple Functions
• ➤ Advanced Tuple Functions
• ➤ Basic Dictionary Functions
• ➤ Advanced Dictionary Functions
• ➤ Conditional Statements : if-elif-else
• ➤ Python 'for' Loop
• ➤ Python 'while' Loop
• ➤ Difference between 'for' loop and 'while' loop
• ➤ Introducing Python Functions

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