How do you end a for loop early in python?

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Break and Continue

Break and continue are two ways to modify the behavior of for loops and while loops.

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Break and Continue
How do you end a for loop early?
Can you break a for loop Python?
How do you stop a running loop in Python?

Break

In Python, the keyword break causes the program to exit a loop early. break causes the program to jump out of for loops even if the for loop hasn't run the specified number of times.break causes the program to jump out of while loops even if the logical condition that defines the loop is still True.

An example using break in a for loop is below.

In [1]:

for i in range(100):
    print(i)
    if i == 3:
        break
print('Loop exited')

When the loop hits i=3, break is encountered and the program exits the loop.

An example using break in a while loop is below.

In [2]:

while True:
    out = input('type q to exit the loop: ')
    if out == 'q':
        break
print('Loop exited')

type q to exit the loop: no
type q to exit the loop: q
Loop exited

Continue

In Python, the keyword continue causes the program to stop running code in a loop and start back at the top of the loop. Remember the keyword break cause the program to exit a loop. continue is similar, but continue causes the program to stop the current iteration of the loop and start the next iteration at the top of the loop.

A code section that uses continue in a for loop is below.

In [3]:

for i in range(4):
    if i==2:
        continue
    print(i)

When the code section is run, the number 2 is not printed. This is because when i=2 the program hits the continue statement. Therefore, the line print(i) isn't run when i=2. Then the program starts back up at the start of the loop with the next number i=3.

How do I leave a loop early in python?

for a in b:
    if criteria in list1:
        print "oh no"
        #Force loop i.e. force next iteration without going on
    someList.append(a)

Also, in java you can break out of a loop, is there an equivalent in Python?

How do you end a for loop early in python?

matt wilkie

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asked Feb 2, 2010 at 13:23

1

continue and break is what you want. Python works identically to Java/C++ in this regard.

answered Feb 2, 2010 at 13:25

Max ShawabkehMax Shawabkeh

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1

Firstly, bear in mind it might be possible to do what you want with a list comprehension. So you might be able to use something like:

somelist = [a for a in b if not a.criteria in otherlist]

If you want to leave a loop early in Python you can use break, just like in Java.

>>> for x in xrange(1,6):
...     print x
...     if x == 2:
...         break
...
1
2

If you want to start the next iteration of the loop early you use continue, again just as you would in Java.

>>> for x in xrange(1,6):
...     if x == 2:
...         continue
...     print x
...
1
3
4
5

Here's the documentation for break and continue. This also covers else clauses for loops, which aren't run when you break.

answered Feb 2, 2010 at 13:25

David WebbDavid Webb

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continue and break work exactly like in other programming languages, except that you cannot break to a label (as you can in Java, for example). That means you can only break one loop at a time.

answered Feb 2, 2010 at 13:28

AndiDogAndiDog

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Take a look at break and continue.

answered Feb 2, 2010 at 13:25

YacobyYacoby

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