Is there a difference between `continue` and `pass` in a for loop in python?

问题

Is there any significant difference between the two python keywords continue and pass like in the examples

for element in some_list:
    if not element:
        pass

and

for element in some_list:
    if not element:
        continue

I should be aware of?

回答1:

Yes, they do completely different things. pass simply does nothing, while continue goes on with the next loop iteration. In your example, the difference would become apparent if you added another statement after the if: After executing pass, this further statement would be executed. After continue, it wouldn't.

>>> a = [0, 1, 2]
>>> for element in a:
...     if not element:
...         pass
...     print element
... 
0
1
2
>>> for element in a:
...     if not element:
...         continue
...     print element
... 
1
2

回答2:

Yes, there is a difference. continue forces the loop to start at the next iteration while pass means "there is no code to execute here" and will continue through the remainder or the loop body.

Run these and see the difference:

for element in some_list:
    if not element:
        pass
    print 1 # will print after pass

for element in some_list:
   if not element:
       continue
   print 1 # will not print after continue

回答3:

continue will jump back to the top of the loop. pass will continue processing.

if pass is at the end for the loop, the difference is negligible as the flow would just back to the top of the loop anyway.

回答4:

In your example, there will be no difference, since both statements appear at the end of the loop. pass is simply a placeholder, in that it does nothing (it passes execution to the next statement). continue, on the other hand, has a definite purpose: it tells the loop to continue as if it had just restarted.

for element in some_list:
    if not element:
        pass
    print element

is very different from

for element in some_list:
    if not element:
        continue
    print element

回答5:

There is a difference between them,
continue skips the loop's current iteration and executes the next iteration.
pass does nothing. It’s an empty statement placeholder.
I would rather give you an example, which will clarify this more better.

>>> for element in some_list:
...     if element == 1:
...         print "Pass executed"
...         pass
...     print element
... 
0
Pass executed
1
2

>>> for element in some_list:
...     if element == 1:
...         print "Continue executed"
...         continue
...     print element
... 
0
Continue executed
2

回答6:

In those examples, no. If the statement is not the very last in the loop then they have very different effects.

回答7:

Yes, there is a difference. Continue actually skips the rest of the current iteration of the loop (returning to the beginning). Pass is a blank statement that does nothing.

See the python docs

回答8:

x = [1,2,3,4] 
for i in x:
    if i==2:
         pass  #Pass actually does nothing. It continues to execute statements below it.
         print "This statement is from pass."
for i in x:
    if i==2:
         continue #Continue gets back to top of the loop.And statements below continue are executed.
         print "This statement is from continue."

The output is

>>> This statement is from pass.

Again, let run same code with minor changes.

x = [1,2,3,4]
for i in x:
    if i==2:
       pass  #Pass actually does nothing. It continues to execute statements below it.
    print "This statement is from pass."
for i in x:
    if i==2:
        continue #Continue gets back to top of the loop.And statements below continue are executed.
    print "This statement is from continue."

The output is -

>>> This statement is from pass.
This statement is from pass.
This statement is from pass.
This statement is from pass.
This statement is from continue.
This statement is from continue.
This statement is from continue.

Pass doesn't do anything. Computation is unaffected. But continue gets back to top of the loop to procced with next computation.

回答9:

Consider it this way:

Pass: Python works purely on indentation! There are no empty curly braces, unlike other languages.

So, if you want to do nothing in case a condition is true there is no option other than pass.

Continue: This is useful only in case of loops. In case, for a range of values, you don't want to execute the remaining statements of the loop after that condition is true for that particular pass, then you will have to use continue.

回答10:

Difference between pass and continue in a for loop:

So why pass in python?

If you want to create a empty class, method or block.

Examples:

class MyException(Exception):
    pass


try:
   1/0
 except:
   pass

without 'pass' in the above examples will throw IndentationError.

来源：https://stackoverflow.com/questions/9483979/is-there-a-difference-between-continue-and-pass-in-a-for-loop-in-python

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python

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