This Python While Loops lesson is for a beginner. Read the short notes, run each example, then change one name or number and run it again.
A while loop repeats as long as its test stays true. Change something inside the loop or it never ends.
break leaves the loop early. continue skips to the next test.
Example 1: Start here
If the printed numbers never change, the test is not moving toward false.
n = 3 # a whole number
while n > 0: # keep repeating while this stays true
print(n)
n -= 1 # update the stored value
print("Go")
Example 2: Count down
The loop stops when n is no longer greater than 0. Forgetting n -= 1 would loop forever.
n = 3 # a whole number
while n > 0: # keep repeating while this stays true
print(n)
n -= 1 # update the stored value
Example 3: Stop with break
break leaves the loop immediately.
n = 0 # a whole number
while True: # keep repeating while this stays true
n += 1 # update the stored value
if n == 3: # run the indented lines only when this is true
break # leave the loop now
print(n)
Example 4: Skip with continue
continue jumps to the next test, so 2 is not printed.
n = 0 # a whole number
while n < 4: # keep repeating while this stays true
n += 1 # update the stored value
if n == 2: # run the indented lines only when this is true
continue # skip the rest of this turn
print(n)
If the printed numbers never change, the test is not moving toward false.
