如何在结束之前停止python脚本

Question

In the main script, I want to stop it under some condition. I tried return but it is wrong since it is outside the function. I tried exit , but it does not stop. See the following:

print 'step 1'
exit
print 'step 2'

what should I do ? the version I used is IDLE 2.7.5+

Answer 1

use exit()

from sys import exit
print 'step 1'
exit()
print 'step 2'

Answer 2

If you're not in a function, use sys.exit()

Note that this will exit python entirely, even if called from a module that's inside a larger program.

It will usually be better organization to return from a function, and keep as much code inside functions as possible.

Answer 3

Another way to exit a Python script is to simply raise the SystemExit exception with raise :

print 'step 1'
raise SystemExit
print 'step 2'

This solution does exactly what sys.exit does, except that you do not need to import sys first.

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Also, your specific problem was caused by the fact that you were not actually calling the exit function:

print 'step 1'
exit() # Add () after exit to call the function
print 'step 2'

However, you should not use this solution because it is considered a bad practice. Instead, you should use sys.exit or raise as shown above.