LM While-Loops

🔁 What is a While-Loop?

A while-loop is a control structure that repeats a block of code as long as a condition is true.

Use it when you don’t know in advance how many times something should repeat — it depends on when the condition becomes false.

a = 7
b = 10

while a <= b:
    print(a)
    a += 1 # a = a + 1

This loop prints values from a to b, stopping once a > b.

If the loop condition never becomes False, the loop runs forever.

a = 0
while a < 5:
    print("Still looping...")
# ❌ a is never changed, so the loop never ends!

✅ To avoid this, always make sure something inside the loop changes the condition.

Sometimes you want to stop a loop before the condition becomes false. Use break for that:

a = 0
while a < 10:
    print(a)
    if a == 4:
        break
    a += 1 # a = a + 1

The loop ends immediately when a == 4 because of the break.

You can also count down using a while-loop:

i = 5
while i > 0:
    print(i)
    i -= 1 # i = i - 1

You can create a loop that runs forever unless you manually stop it using break.

count = 0
while True:
    print("Counting:", count)
    count += 1  # count = count + 1
    if count == 3:
        break

Counting: 0
Counting: 1
Counting: 2

while True is common in programs that wait for user input or conditions, and rely on break to stop.

With the continue statement we can stop the current iteration, and continue with the next:

i = 0
while i < 6:
  i += 1 # i = i + 1
  if i == 3:
    continue
  print(i)

Feature	While-Loop
Repetition Count	Unknown
Condition Placement	Before each iteration
Use Case	Wait for condition to become false
Special Keywords	`break` and `continue`
Common Pattern	`while True:` with internal stop

Use while-loops when repetition depends on changing conditions, not a fixed number.