The break Statement

1How it is written

for value in values:
    statement
    if it is time to stop:
        break
    statement

next statement    <- break jumps here

A single word, on a line of its own, inside the loop body — almost always as the block of an if, because a break with no condition stops the loop on its first round.

2Counting to 9, stopping at 5

# print 1 to 9 — but stop as soon as i reaches 5
for i in range(1, 10):
    if i == 5:
        break
    print(i)

1
2
3
4

The loop was set up for nine rounds and ran four. On the fifth, i == 5 was True, break ran, and that was that — print(i) never ran for 5, and 6, 7, 8 and 9 were never reached at all.

3Move one line and the answer changes

Same loop, same condition, same break — with the print() moved above the if instead of below it:

# the print now comes first
for i in range(1, 10):
    print(i)
    if i == 5:
        break

1
2
3
4
5

Now 5 is printed, because the printing happened before the program reached the break. Statements in a body still run top to bottom; break only stops what comes after it.

4Step through it

The tracer from the last lesson, with the pointer on break. Step to the round where i is 4 and watch the pointer leave the loop body altogether:

nothing yet

5What break is really for: searching

This is the job break was made for. Once you have found what you were looking for, there is nothing to gain by looking at the rest:

# stop looking the moment the name turns up
names = ['Aarav', 'Diya', 'Kabir', 'Meera', 'Rohan']
wanted = 'Kabir'

for name in names:
    print('Checking', name)
    if name == wanted:
        print('Found', wanted)
        break

Checking Aarav
Checking Diya
Checking Kabir
Found Kabir

Meera and Rohan were never checked. On a list of five that is a small saving; on a list of five lakh names it is the difference between a program that answers instantly and one you wait for.

6break with while True

You met while True as the loop that never ends on its own. With break it becomes something genuinely useful: a loop that runs until something inside it decides to stop, rather than until a condition at the top says so.

# keep printing hello until the user types bye
while True:
    choice = input('Enter bye to exit, or anything else for hello: ')
    if choice == 'bye':
        break
    print('hello')

print('Goodbye!')

Enter bye to exit, or anything else for hello: hi
hello
Enter bye to exit, or anything else for hello: ok
hello
Enter bye to exit, or anything else for hello: bye
Goodbye!

The condition True is always true, so the only way out is the break. This is exactly how a game keeps running until the player picks exit from the menu, and it is the standard shape for any “keep going until the user says stop” program.

Try it yourself. The values you type are fed to the program in order:

# add up marks, and stop the moment -1 is typed
total = 0

while True:
    mark = int(input('Enter a mark (-1 to stop): '))
    if mark == -1:
        break
    total = total + mark

print('Total:', total)

7In nested loops, break leaves only the inner one

This is the other place marks are lost. A break ends the loop it is written in — and when loops are nested, that is the inner one. The outer loop carries on as if nothing had happened:

# the break belongs to the inner loop only
for i in range(1, 4):
    for j in range(1, 4):
        if j == 2:
            break
        print(i, j)

1 1
2 1
3 1

The inner loop was cut short on all three of its runs — that is why j is never 2 or 3 in the output. But the outer loop still ran its full three rounds, so i went 1, 2, 3 as usual.

8Recap