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This article describes the use of Python loop else, break and continue a detailed analysis of the Python for loop with examples form, while loop else, break and continue functionality, usage and related handling precautions, refer a friend in need the
examples herein describes the use of Python cycle else, break and continue to. Share to you for your reference, as follows:
Looking at Python's time to see the documents for and while statements and the C language has one of the biggest difference - can have an optional else statement. The implementation of the trigger mechanism of this statement I do not quite understand, through code testing did not know the trigger else statement under what circumstances. "Where there is, are reasonable", Python designers certainly had a purpose, and now we come to explore some.
In order for the statement, for example, the development environment Python3.4.
Else the role of Python loop
presence circulation else is to make the code clearer and more concise. Below is an example for everyone to see, respectively, to achieve the same effect by writing the code with traditional writing and the else
Traditional C for loop format wording
myList = [1,2,3,4,5,6,7]
isFound = False
for item in myList:
if item == 4:
isFound = True
print('List 有 4')
break
if not isFound:
print('List 没有 4')
Else statement written with a for loop
myList = [1,2,3,4,5,6,7]
for item in myList:
if item == 4:
isFound = True
print('List 有 4')
break
else:
print('List 没有 4')
Comparing two codes, not difficult to find compared to traditional loop for writing, with the wording else statements more concise and less isFound this variable and this out of the loop if the judge sentences.
to sum up
Under else structures for ...
for which statements and ordinary (not else for statement) makes no difference;
else statements will be executed after the implementation of the normal cycle;
when for the statement is interrupted by the break out of, will not be executed else.
Concluded one, for ... else structure is generally used together and break in order to reflect the power of this structure (at least I think so, I do not know what other cases, users want to let me know).
while ... else structure also meets the above criteria.
Python cycle continue and break
continue and break statement in fact and use C language is the same, just for ... else structure structure
When the for statement interrupted by a break in the jump, will not execute the contents else;
and will continue unusual statement and the statement is no different, if not not break through, there continue light will enter the else statement.
continue code sample
code show as below:
for x in range(1, 4):
print(x, 'for语句')
continue
print(x, 'continue语句后')
else:
print(x, 'else语句')
Results of the:
Statement 1 for
2 for statements
3 for sentence
3 else statements
break code sample
code show as below:
for x in range(1, 4):
print(x, 'for语句')
break
print(x, 'break语句后')
else:
print(x, 'else语句')
Results of the:
1 for statement
Thank you very much to read
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