Python: 'break' outside loop

in the following python code:

narg=len(sys.argv)
print "@length arg= ", narg
if narg == 1:
 print "@Usage: input_filename nelements nintervals"
 break

I get:

SyntaxError: 'break' outside loop

Why?

edited Aug 4 '16 at 11:45

Serenity

18.8k115572

asked Mar 17 '10 at 13:32

Open the way

7,15238115179

4

What do you think break does here? What do you expect to happen?

– S.Lott
Mar 17 '10 at 13:35

2

The optparse module (or similar) will make parsing argv much simpler. docs.python.org/library/optparse.html

– Roger Pate
Mar 17 '10 at 13:36

add a comment |

in the following python code:

narg=len(sys.argv)
print "@length arg= ", narg
if narg == 1:
 print "@Usage: input_filename nelements nintervals"
 break

I get:

SyntaxError: 'break' outside loop

Why?

edited Aug 4 '16 at 11:45

Serenity

18.8k115572

asked Mar 17 '10 at 13:32

Open the way

7,15238115179

4

What do you think break does here? What do you expect to happen?

– S.Lott
Mar 17 '10 at 13:35

2

The optparse module (or similar) will make parsing argv much simpler. docs.python.org/library/optparse.html

– Roger Pate
Mar 17 '10 at 13:36

add a comment |

in the following python code:

narg=len(sys.argv)
print "@length arg= ", narg
if narg == 1:
 print "@Usage: input_filename nelements nintervals"
 break

I get:

SyntaxError: 'break' outside loop

Why?

edited Aug 4 '16 at 11:45

Serenity

18.8k115572

asked Mar 17 '10 at 13:32

Open the way

7,15238115179

in the following python code:

narg=len(sys.argv)
print "@length arg= ", narg
if narg == 1:
 print "@Usage: input_filename nelements nintervals"
 break

I get:

SyntaxError: 'break' outside loop

Why?

python

edited Aug 4 '16 at 11:45

Serenity

18.8k115572

asked Mar 17 '10 at 13:32

Open the way

7,15238115179

edited Aug 4 '16 at 11:45

Serenity

18.8k115572

asked Mar 17 '10 at 13:32

Open the way

7,15238115179

edited Aug 4 '16 at 11:45

Serenity

18.8k115572

edited Aug 4 '16 at 11:45

Serenity

18.8k115572

edited Aug 4 '16 at 11:45

Serenity

18.8k115572

asked Mar 17 '10 at 13:32

Open the way

7,15238115179

asked Mar 17 '10 at 13:32

Open the way

7,15238115179

asked Mar 17 '10 at 13:32

Open the way

7,15238115179

4

What do you think break does here? What do you expect to happen?

– S.Lott
Mar 17 '10 at 13:35

2

The optparse module (or similar) will make parsing argv much simpler. docs.python.org/library/optparse.html

– Roger Pate
Mar 17 '10 at 13:36

add a comment |

4

What do you think break does here? What do you expect to happen?

– S.Lott
Mar 17 '10 at 13:35

2

The optparse module (or similar) will make parsing argv much simpler. docs.python.org/library/optparse.html

– Roger Pate
Mar 17 '10 at 13:36

What do you think break does here? What do you expect to happen?

– S.Lott
Mar 17 '10 at 13:35

The optparse module (or similar) will make parsing argv much simpler. docs.python.org/library/optparse.html

– Roger Pate
Mar 17 '10 at 13:36

add a comment |

4 Answers
4

active

oldest

votes

Because break cannot be used to break out of an if - it can only break out of loops. That's the way Python (and most other languages) are specified to behave.

What are you trying to do? Perhaps you should use sys.exit() or return instead?

answered Mar 17 '10 at 13:34

Mark Byers

598k12713701348

1

and how could I do so the scripts stops here?

– Open the way
Mar 17 '10 at 13:35

6

sys.exit() terminates the program immediately.

– Mark Byers
Mar 17 '10 at 13:36

2

raise SystemExit terminates the program; sys.exit() raises it, if you prefer a function call.

– tzot
Apr 4 '10 at 8:24

add a comment |

Because the break statement is intended to break out of loops. You don't need to break out of an if statement - it just ends at the end.

answered Mar 17 '10 at 13:35

Steve314

21.8k1049110

add a comment |

Because break can only be used inside a loop.
It is used to break out of a loop (stop the loop).

answered Mar 17 '10 at 13:35

enricog

2,86052746

add a comment |

break breaks out of a loop, not an if statement, as others have pointed out. The motivation for this isn't too hard to see; think about code like

for item in some_iterable:
 ...
 if break_condition():
 break

The break would be pretty useless if it terminated the if block rather than terminated the loop -- terminating a loop conditionally is the exact thing break is used for.

edited Nov 15 '18 at 5:27

answered Mar 17 '10 at 16:17

Mike Graham

51.4k1076116

Is your last sentence equivalent to "A break should only be used directly inside a loop."?

– Quetzalcoatl
Nov 12 '18 at 2:42

@Quetzalcoatl I don't think so. What do you mean "directly"?

– Mike Graham
Nov 14 '18 at 6:17

a break in a loop, where this break is not under a condition. the code in your response is a case where break is not "directly" in the loop -- it is inside of a condition. somehow your last sentence was grammatically unclear to me :-)

– Quetzalcoatl
Nov 15 '18 at 0:18

1

@Quetzalcoatl I rephrased -- I was trying to say that you would never put break directly inside a loop. You always put it inside an if inside a loop.

– Mike Graham
Nov 15 '18 at 5:28

add a comment |

StackExchange.ifUsing("editor", function ()
StackExchange.using("externalEditor", function ()
StackExchange.using("snippets", function ()
StackExchange.snippets.init();
);
);
, "code-snippets");

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "1"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);

);

draft saved

draft discarded

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f2462566%2fpython-break-outside-loop%23new-answer', 'question_page');

);

Post as a guest

Name

Required, but never shown

4 Answers
4

active

oldest

votes

4 Answers
4

active

oldest

votes

Because break cannot be used to break out of an if - it can only break out of loops. That's the way Python (and most other languages) are specified to behave.

What are you trying to do? Perhaps you should use sys.exit() or return instead?

answered Mar 17 '10 at 13:34

Mark Byers

598k12713701348

1

and how could I do so the scripts stops here?

– Open the way
Mar 17 '10 at 13:35

6

sys.exit() terminates the program immediately.

– Mark Byers
Mar 17 '10 at 13:36

2

raise SystemExit terminates the program; sys.exit() raises it, if you prefer a function call.

– tzot
Apr 4 '10 at 8:24

add a comment |

Because break cannot be used to break out of an if - it can only break out of loops. That's the way Python (and most other languages) are specified to behave.

What are you trying to do? Perhaps you should use sys.exit() or return instead?

answered Mar 17 '10 at 13:34

Mark Byers

598k12713701348

1

and how could I do so the scripts stops here?

– Open the way
Mar 17 '10 at 13:35

6

sys.exit() terminates the program immediately.

– Mark Byers
Mar 17 '10 at 13:36

2

raise SystemExit terminates the program; sys.exit() raises it, if you prefer a function call.

– tzot
Apr 4 '10 at 8:24

add a comment |

Because break cannot be used to break out of an if - it can only break out of loops. That's the way Python (and most other languages) are specified to behave.

What are you trying to do? Perhaps you should use sys.exit() or return instead?

answered Mar 17 '10 at 13:34

Mark Byers

598k12713701348

Because break cannot be used to break out of an if - it can only break out of loops. That's the way Python (and most other languages) are specified to behave.

What are you trying to do? Perhaps you should use sys.exit() or return instead?

answered Mar 17 '10 at 13:34

Mark Byers

598k12713701348

answered Mar 17 '10 at 13:34

Mark Byers

598k12713701348

answered Mar 17 '10 at 13:34

Mark Byers

598k12713701348

answered Mar 17 '10 at 13:34

Mark Byers

598k12713701348

1

and how could I do so the scripts stops here?

– Open the way
Mar 17 '10 at 13:35

6

sys.exit() terminates the program immediately.

– Mark Byers
Mar 17 '10 at 13:36

2

raise SystemExit terminates the program; sys.exit() raises it, if you prefer a function call.

– tzot
Apr 4 '10 at 8:24

add a comment |

1

and how could I do so the scripts stops here?

– Open the way
Mar 17 '10 at 13:35

6

sys.exit() terminates the program immediately.

– Mark Byers
Mar 17 '10 at 13:36

2

raise SystemExit terminates the program; sys.exit() raises it, if you prefer a function call.

– tzot
Apr 4 '10 at 8:24

and how could I do so the scripts stops here?

– Open the way
Mar 17 '10 at 13:35

sys.exit() terminates the program immediately.

– Mark Byers
Mar 17 '10 at 13:36

raise SystemExit terminates the program; sys.exit() raises it, if you prefer a function call.

– tzot
Apr 4 '10 at 8:24

add a comment |

Because the break statement is intended to break out of loops. You don't need to break out of an if statement - it just ends at the end.

answered Mar 17 '10 at 13:35

Steve314

21.8k1049110

add a comment |

Because the break statement is intended to break out of loops. You don't need to break out of an if statement - it just ends at the end.

answered Mar 17 '10 at 13:35

Steve314

21.8k1049110

add a comment |

Because the break statement is intended to break out of loops. You don't need to break out of an if statement - it just ends at the end.

answered Mar 17 '10 at 13:35

Steve314

21.8k1049110

Because the break statement is intended to break out of loops. You don't need to break out of an if statement - it just ends at the end.

answered Mar 17 '10 at 13:35

Steve314

21.8k1049110

answered Mar 17 '10 at 13:35

Steve314

21.8k1049110

answered Mar 17 '10 at 13:35

Steve314

21.8k1049110

answered Mar 17 '10 at 13:35

Steve314

21.8k1049110

add a comment |

Because break can only be used inside a loop.
It is used to break out of a loop (stop the loop).

answered Mar 17 '10 at 13:35

enricog

2,86052746

add a comment |

Because break can only be used inside a loop.
It is used to break out of a loop (stop the loop).

answered Mar 17 '10 at 13:35

enricog

2,86052746

add a comment |

Because break can only be used inside a loop.
It is used to break out of a loop (stop the loop).

answered Mar 17 '10 at 13:35

enricog

2,86052746

Because break can only be used inside a loop.
It is used to break out of a loop (stop the loop).

answered Mar 17 '10 at 13:35

enricog

2,86052746

answered Mar 17 '10 at 13:35

enricog

2,86052746

answered Mar 17 '10 at 13:35

enricog

2,86052746

answered Mar 17 '10 at 13:35

enricog

2,86052746

add a comment |

break breaks out of a loop, not an if statement, as others have pointed out. The motivation for this isn't too hard to see; think about code like

for item in some_iterable:
 ...
 if break_condition():
 break

The break would be pretty useless if it terminated the if block rather than terminated the loop -- terminating a loop conditionally is the exact thing break is used for.

edited Nov 15 '18 at 5:27

answered Mar 17 '10 at 16:17

Mike Graham

51.4k1076116

Is your last sentence equivalent to "A break should only be used directly inside a loop."?

– Quetzalcoatl
Nov 12 '18 at 2:42

@Quetzalcoatl I don't think so. What do you mean "directly"?

– Mike Graham
Nov 14 '18 at 6:17

a break in a loop, where this break is not under a condition. the code in your response is a case where break is not "directly" in the loop -- it is inside of a condition. somehow your last sentence was grammatically unclear to me :-)

– Quetzalcoatl
Nov 15 '18 at 0:18

1

@Quetzalcoatl I rephrased -- I was trying to say that you would never put break directly inside a loop. You always put it inside an if inside a loop.

– Mike Graham
Nov 15 '18 at 5:28

add a comment |

break breaks out of a loop, not an if statement, as others have pointed out. The motivation for this isn't too hard to see; think about code like

for item in some_iterable:
 ...
 if break_condition():
 break

The break would be pretty useless if it terminated the if block rather than terminated the loop -- terminating a loop conditionally is the exact thing break is used for.

edited Nov 15 '18 at 5:27

answered Mar 17 '10 at 16:17

Mike Graham

51.4k1076116

Is your last sentence equivalent to "A break should only be used directly inside a loop."?

– Quetzalcoatl
Nov 12 '18 at 2:42

@Quetzalcoatl I don't think so. What do you mean "directly"?

– Mike Graham
Nov 14 '18 at 6:17

a break in a loop, where this break is not under a condition. the code in your response is a case where break is not "directly" in the loop -- it is inside of a condition. somehow your last sentence was grammatically unclear to me :-)

– Quetzalcoatl
Nov 15 '18 at 0:18

1

@Quetzalcoatl I rephrased -- I was trying to say that you would never put break directly inside a loop. You always put it inside an if inside a loop.

– Mike Graham
Nov 15 '18 at 5:28

add a comment |

break breaks out of a loop, not an if statement, as others have pointed out. The motivation for this isn't too hard to see; think about code like

for item in some_iterable:
 ...
 if break_condition():
 break

The break would be pretty useless if it terminated the if block rather than terminated the loop -- terminating a loop conditionally is the exact thing break is used for.

edited Nov 15 '18 at 5:27

answered Mar 17 '10 at 16:17

Mike Graham

51.4k1076116

break breaks out of a loop, not an if statement, as others have pointed out. The motivation for this isn't too hard to see; think about code like

for item in some_iterable:
 ...
 if break_condition():
 break

The break would be pretty useless if it terminated the if block rather than terminated the loop -- terminating a loop conditionally is the exact thing break is used for.

edited Nov 15 '18 at 5:27

answered Mar 17 '10 at 16:17

Mike Graham

51.4k1076116

edited Nov 15 '18 at 5:27

answered Mar 17 '10 at 16:17

Mike Graham

51.4k1076116

answered Mar 17 '10 at 16:17

Mike Graham

51.4k1076116

answered Mar 17 '10 at 16:17

Mike Graham

51.4k1076116

Is your last sentence equivalent to "A break should only be used directly inside a loop."?

– Quetzalcoatl
Nov 12 '18 at 2:42

@Quetzalcoatl I don't think so. What do you mean "directly"?

– Mike Graham
Nov 14 '18 at 6:17

a break in a loop, where this break is not under a condition. the code in your response is a case where break is not "directly" in the loop -- it is inside of a condition. somehow your last sentence was grammatically unclear to me :-)

– Quetzalcoatl
Nov 15 '18 at 0:18

1

@Quetzalcoatl I rephrased -- I was trying to say that you would never put break directly inside a loop. You always put it inside an if inside a loop.

– Mike Graham
Nov 15 '18 at 5:28

add a comment |

Is your last sentence equivalent to "A break should only be used directly inside a loop."?

– Quetzalcoatl
Nov 12 '18 at 2:42

@Quetzalcoatl I don't think so. What do you mean "directly"?

– Mike Graham
Nov 14 '18 at 6:17

a break in a loop, where this break is not under a condition. the code in your response is a case where break is not "directly" in the loop -- it is inside of a condition. somehow your last sentence was grammatically unclear to me :-)

– Quetzalcoatl
Nov 15 '18 at 0:18

1

@Quetzalcoatl I rephrased -- I was trying to say that you would never put break directly inside a loop. You always put it inside an if inside a loop.

– Mike Graham
Nov 15 '18 at 5:28

Is your last sentence equivalent to "A break should only be used directly inside a loop."?

– Quetzalcoatl
Nov 12 '18 at 2:42

@Quetzalcoatl I don't think so. What do you mean "directly"?

– Mike Graham
Nov 14 '18 at 6:17

a break in a loop, where this break is not under a condition. the code in your response is a case where break is not "directly" in the loop -- it is inside of a condition. somehow your last sentence was grammatically unclear to me :-)

– Quetzalcoatl
Nov 15 '18 at 0:18

@Quetzalcoatl I rephrased -- I was trying to say that you would never put break directly inside a loop. You always put it inside an if inside a loop.

– Mike Graham
Nov 15 '18 at 5:28

add a comment |

draft saved

draft discarded

Thanks for contributing an answer to Stack Overflow!

Please be sure to answer the question. Provide details and share your research!

But avoid …

Asking for help, clarification, or responding to other answers.

Making statements based on opinion; back them up with references or personal experience.

To learn more, see our tips on writing great answers.

draft saved

draft discarded

Post as a guest

Name

Required, but never shown

Name

Required, but never shown

Name

Required, but never shown

This page is only for reference, If you need detailed information, please check here

搜尋此網誌

Pfthb