Loops: for and while

In programming, we often need to repeat actions — like printing items, summing values, or checking conditions. Loops let us do this efficiently without writing the same line multiple times.

Python offers two main types of loops: for and while.

A for loop is used when you want to iterate over a sequence (like a list, string, or range of numbers).

복사
fruits = ["apple", "banana", "cherry"]

for fruit in fruits:
    print("I like", fruit)

• fruits is a list.
• The variable fruit takes one value from the list on each loop.
• The loop prints a sentence using that value.
• This repeats three times — once for each fruit.

A while loop runs as long as a condition is true.

복사
count = 1

while count <= 3:
    print("Count is:", count)
    count += 1

• The loop starts with count = 1.
• It checks the condition count <= 3. If true, it runs the block.
• After each loop, count increases by 1.
• When count becomes 4, the loop stops.

• Use a for loop when you have a known set of items.
• Use a while loop when you have a condition that might change over time.

Next, you’ll learn how to control loop flow using break, continue, and pass.