Detailed Explanation of Usage Examples of else break and continue in Python Cycle

This article illustrates the use of else, break, and continue in the Python loop. Share it for your reference, as follows:

I saw it when I looked at the documentation of Python for And while Statement is one of the biggest differences from C language-you can have one optional else Statement. The execution trigger mechanism of this statement is not clear to me, and it is only through code testing that I know under what circumstances it triggers else Statement. "Every existence is reasonable." The designer of Python must have his purpose. Now let's explore it once.

Taking for statement as an example, the development environment Python3.4.

Effect of else in Python Cycle

In a loop else The existence of is to make the code clearer and more concise. Here's an example to show you, using traditional writing and tape respectively else The writing method of realizes the code with the same function

for Loop Writing of Traditional C Format

myList = [1,2,3,4,5,6,7]
isFound = False
for item in myList:
  if item == 4:
    isFound = True
    print('List  Have  4')
    break
if not isFound:
  print('List  No  4')

Belt else Statement for Circular writing

myList = [1,2,3,4,5,6,7]
  for item in myList:
  if item == 4:
    isFound = True
    print('List  Have  4')
    break
else:
  print('List  No  4')

Comparing the two codes, it is not difficult to find that compared with the traditional for Loop writing, with else The statement is written more concisely, and the isFound variable and the if judgment statement after jumping out of the loop are missing.

Summarize

Under the structure of for … else

There is no difference between the statements in for and ordinary (for statement without else); Statements in else are executed after the loop executes normally; else is not executed when the statement in for is interrupted by break jumping out.

Finally, it summarizes a sentence, for... else structure 1 and while0 1 use, in order to reflect the strength of this structure (at least I think so, I don't know what other situations, I hope netizens will not hesitate to comment).

while... else structure also meets the above conditions.

continue and break in Python Cycle

continue And while0 Statement is actually the same as the usage of C language, only in for... else structure

When for The statement in passes the while0 When jumping out and interrupting, it will not be executed again else The contents in; And will continue Statement is no different from ordinary statement, as long as it is not failed while0 , light has continue Will enter else Statement.

continue Code Sample

The code is as follows:

for x in range(1, 4):
  print(x, 'for Statement ')
  continue
  print(x, 'continue After statement ')
else:
  print(x, 'else Statement ')

Implementation results:

1 for statement
2 for statement
3 for statement
3 else statement

break Code Sample

The code is as follows:

for x in range(1, 4):
  print(x, 'for Statement ')
  break
  print(x, 'break After statement ')
else:
  print(x, 'else Statement ')

Implementation results:

1 for statement

For more readers interested in Python related contents, please check the topics of this site: "Introduction and Advanced Classic Tutorial of Python", "Data Structure and Algorithm Tutorial of Python", "Summary of Function Use Skills of Python", "Summary of String Operation Skills of Python" and "Summary of File and Directory Operation Skills of Python"

I hope this article is helpful to everyone's Python programming.