Bug with re.finditer() function and re.DOTALL flag in re module of Python 3.6? [duplicate]

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This question already has an answer here:

• 
  Python regex: greedy pattern returning multiple empty matches
  
  1 answer
  
  


• 
  Regex plus vs star difference?
  
  9 answers
  
  


• 
  String.replaceAll(regex) makes the same replacement twice
  
  1 answer
  
  

I'm getting weird results when I use the re.DOTALL in re.finditer() when using Python 3.6.
I don't know if this is the expected operation or If I'm missing something or if its a bug.

CASE 1

I try this version of a string with an embedded newline.

I expect to get 2 matched values back: m1 = 'abc' and m2 = ' de'

import re

result = re.finditer('.*', 'abcn de', flags=0)

m1 = result.__next__()

#    <_sre.SRE_Match object; span=(0, 3), match='abc'>

m2 = result.__next__()

#    <_sre.SRE_Match object; span=(3, 3), match=''>

m3 = result.__next__()

#    <_sre.SRE_Match object; span=(4, 7), match=' de'>

m4 = result.__next__()

#    <_sre.SRE_Match object; span=(7, 7), match=''>

Whats with the match values m2 and m4?

CASE 2

I try this with re.DOTALL, and I expect to get back one match, m1 = 'abcn de'

result = re.finditer('.*', 'abcn de', flags=re.DOTALL)

m1 = result.__next__()

#     <_sre.SRE_Match object; span=(0, 7), match='abcn de'>

m2 = result.__next__()

#     <_sre.SRE_Match object; span=(7, 7), match=''>

Whats with the extra matches? How do I make the results work as expected?

I want the first case to return ...

m1 = 'abc'

m2 = ' de'

... and the second case to return

m1 = 'abcn de'

and nothing else.

python regex pattern-matching newline flags

share|improve this question

asked Jan 3 at 2:55

P MoranP Moran

4071614

marked as duplicate by James, Wiktor Stribiżew python
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Jan 3 at 7:46

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  If you don't want to match empty strings, use .+ instead of .*.
  
  – Tim Peters
  Jan 3 at 2:58
  

  
  
  
  

add a comment | 

0

This question already has an answer here:

• 
  Python regex: greedy pattern returning multiple empty matches
  
  1 answer
  
  


• 
  Regex plus vs star difference?
  
  9 answers
  
  


• 
  String.replaceAll(regex) makes the same replacement twice
  
  1 answer
  
  

I'm getting weird results when I use the re.DOTALL in re.finditer() when using Python 3.6.
I don't know if this is the expected operation or If I'm missing something or if its a bug.

CASE 1

I try this version of a string with an embedded newline.

I expect to get 2 matched values back: m1 = 'abc' and m2 = ' de'

import re

result = re.finditer('.*', 'abcn de', flags=0)

m1 = result.__next__()

#    <_sre.SRE_Match object; span=(0, 3), match='abc'>

m2 = result.__next__()

#    <_sre.SRE_Match object; span=(3, 3), match=''>

m3 = result.__next__()

#    <_sre.SRE_Match object; span=(4, 7), match=' de'>

m4 = result.__next__()

#    <_sre.SRE_Match object; span=(7, 7), match=''>

Whats with the match values m2 and m4?

CASE 2

I try this with re.DOTALL, and I expect to get back one match, m1 = 'abcn de'

result = re.finditer('.*', 'abcn de', flags=re.DOTALL)

m1 = result.__next__()

#     <_sre.SRE_Match object; span=(0, 7), match='abcn de'>

m2 = result.__next__()

#     <_sre.SRE_Match object; span=(7, 7), match=''>

Whats with the extra matches? How do I make the results work as expected?

I want the first case to return ...

m1 = 'abc'

m2 = ' de'

... and the second case to return

m1 = 'abcn de'

and nothing else.

python regex pattern-matching newline flags

share|improve this question

asked Jan 3 at 2:55

P MoranP Moran

4071614

marked as duplicate by James, Wiktor Stribiżew python
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Jan 3 at 7:46

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  If you don't want to match empty strings, use .+ instead of .*.
  
  – Tim Peters
  Jan 3 at 2:58
  

  
  
  
  

add a comment | 

0

0

0

This question already has an answer here:

• 
  Python regex: greedy pattern returning multiple empty matches
  
  1 answer
  
  


• 
  Regex plus vs star difference?
  
  9 answers
  
  


• 
  String.replaceAll(regex) makes the same replacement twice
  
  1 answer
  
  

I'm getting weird results when I use the re.DOTALL in re.finditer() when using Python 3.6.
I don't know if this is the expected operation or If I'm missing something or if its a bug.

CASE 1

I try this version of a string with an embedded newline.

I expect to get 2 matched values back: m1 = 'abc' and m2 = ' de'

import re

result = re.finditer('.*', 'abcn de', flags=0)

m1 = result.__next__()

#    <_sre.SRE_Match object; span=(0, 3), match='abc'>

m2 = result.__next__()

#    <_sre.SRE_Match object; span=(3, 3), match=''>

m3 = result.__next__()

#    <_sre.SRE_Match object; span=(4, 7), match=' de'>

m4 = result.__next__()

#    <_sre.SRE_Match object; span=(7, 7), match=''>

Whats with the match values m2 and m4?

CASE 2

I try this with re.DOTALL, and I expect to get back one match, m1 = 'abcn de'

result = re.finditer('.*', 'abcn de', flags=re.DOTALL)

m1 = result.__next__()

#     <_sre.SRE_Match object; span=(0, 7), match='abcn de'>

m2 = result.__next__()

#     <_sre.SRE_Match object; span=(7, 7), match=''>

Whats with the extra matches? How do I make the results work as expected?

I want the first case to return ...

m1 = 'abc'

m2 = ' de'

... and the second case to return

m1 = 'abcn de'

and nothing else.

python regex pattern-matching newline flags

share|improve this question

asked Jan 3 at 2:55

P MoranP Moran

4071614

This question already has an answer here:

• 
  Python regex: greedy pattern returning multiple empty matches
  
  1 answer
  
  


• 
  Regex plus vs star difference?
  
  9 answers
  
  


• 
  String.replaceAll(regex) makes the same replacement twice
  
  1 answer
  
  

I'm getting weird results when I use the re.DOTALL in re.finditer() when using Python 3.6.
I don't know if this is the expected operation or If I'm missing something or if its a bug.

CASE 1

I try this version of a string with an embedded newline.

I expect to get 2 matched values back: m1 = 'abc' and m2 = ' de'

import re

result = re.finditer('.*', 'abcn de', flags=0)

m1 = result.__next__()

#    <_sre.SRE_Match object; span=(0, 3), match='abc'>

m2 = result.__next__()

#    <_sre.SRE_Match object; span=(3, 3), match=''>

m3 = result.__next__()

#    <_sre.SRE_Match object; span=(4, 7), match=' de'>

m4 = result.__next__()

#    <_sre.SRE_Match object; span=(7, 7), match=''>

Whats with the match values m2 and m4?

CASE 2

I try this with re.DOTALL, and I expect to get back one match, m1 = 'abcn de'

result = re.finditer('.*', 'abcn de', flags=re.DOTALL)

m1 = result.__next__()

#     <_sre.SRE_Match object; span=(0, 7), match='abcn de'>

m2 = result.__next__()

#     <_sre.SRE_Match object; span=(7, 7), match=''>

Whats with the extra matches? How do I make the results work as expected?

I want the first case to return ...

m1 = 'abc'

m2 = ' de'

... and the second case to return

m1 = 'abcn de'

and nothing else.

This question already has an answer here:

• 
  Python regex: greedy pattern returning multiple empty matches
  
  1 answer
  
  


• 
  Regex plus vs star difference?
  
  9 answers
  
  


• 
  String.replaceAll(regex) makes the same replacement twice
  
  1 answer
  
  

python regex pattern-matching newline flags

python regex pattern-matching newline flags

share|improve this question

asked Jan 3 at 2:55

P MoranP Moran

4071614

share|improve this question

asked Jan 3 at 2:55

P MoranP Moran

4071614

share|improve this question

share|improve this question

asked Jan 3 at 2:55

P MoranP Moran

4071614

asked Jan 3 at 2:55

P MoranP Moran

4071614

asked Jan 3 at 2:55

P MoranP Moran

4071614

4071614

marked as duplicate by James, Wiktor Stribiżew python
Users with the  python badge can single-handedly close python questions as duplicates and reopen them as needed.

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Jan 3 at 7:46

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

marked as duplicate by James, Wiktor Stribiżew python
Users with the  python badge can single-handedly close python questions as duplicates and reopen them as needed.

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Jan 3 at 7:46

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  If you don't want to match empty strings, use .+ instead of .*.
  
  – Tim Peters
  Jan 3 at 2:58
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  If you don't want to match empty strings, use .+ instead of .*.
  
  – Tim Peters
  Jan 3 at 2:58
  

  
  
  
  

If you don't want to match empty strings, use .+ instead of .*.

– Tim Peters
Jan 3 at 2:58

If you don't want to match empty strings, use .+ instead of .*.

– Tim Peters
Jan 3 at 2:58

add a comment | 

1 Answer
1

active

oldest

votes

1

Your pattern is

.*

This means "match zero or more characters"; zero-width matches are permitted.

In your first case, the m2 and m4s exist because the pattern stops matching at the newline, then tries to find a new match starting at that position (index 3). No characters are matched, but the pattern still permits it, because it's .*, hence the first match has

span=(0, 3)

and the second match has

span=(3, 3)

The same thing is happening for span=(7, 7) in m4 and in your DOTALL code.

It sounds like you want a match only if there's at least one character - repeat with + rather than *:

re.finditer('.+', 'abcn de')

share|improve this answer

answered Jan 3 at 3:01

CertainPerformanceCertainPerformance

97.5k165887

add a comment | 

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

active

oldest

votes

active

oldest

votes

1

Your pattern is

.*

This means "match zero or more characters"; zero-width matches are permitted.

In your first case, the m2 and m4s exist because the pattern stops matching at the newline, then tries to find a new match starting at that position (index 3). No characters are matched, but the pattern still permits it, because it's .*, hence the first match has

span=(0, 3)

and the second match has

span=(3, 3)

The same thing is happening for span=(7, 7) in m4 and in your DOTALL code.

It sounds like you want a match only if there's at least one character - repeat with + rather than *:

re.finditer('.+', 'abcn de')

share|improve this answer

answered Jan 3 at 3:01

CertainPerformanceCertainPerformance

97.5k165887

add a comment | 

1

Your pattern is

.*

This means "match zero or more characters"; zero-width matches are permitted.

In your first case, the m2 and m4s exist because the pattern stops matching at the newline, then tries to find a new match starting at that position (index 3). No characters are matched, but the pattern still permits it, because it's .*, hence the first match has

span=(0, 3)

and the second match has

span=(3, 3)

The same thing is happening for span=(7, 7) in m4 and in your DOTALL code.

It sounds like you want a match only if there's at least one character - repeat with + rather than *:

re.finditer('.+', 'abcn de')

share|improve this answer

answered Jan 3 at 3:01

CertainPerformanceCertainPerformance

97.5k165887

add a comment | 

1

1

1

Your pattern is

.*

This means "match zero or more characters"; zero-width matches are permitted.

In your first case, the m2 and m4s exist because the pattern stops matching at the newline, then tries to find a new match starting at that position (index 3). No characters are matched, but the pattern still permits it, because it's .*, hence the first match has

span=(0, 3)

and the second match has

span=(3, 3)

The same thing is happening for span=(7, 7) in m4 and in your DOTALL code.

It sounds like you want a match only if there's at least one character - repeat with + rather than *:

re.finditer('.+', 'abcn de')

share|improve this answer

answered Jan 3 at 3:01

CertainPerformanceCertainPerformance

97.5k165887

Your pattern is

.*

This means "match zero or more characters"; zero-width matches are permitted.

In your first case, the m2 and m4s exist because the pattern stops matching at the newline, then tries to find a new match starting at that position (index 3). No characters are matched, but the pattern still permits it, because it's .*, hence the first match has

span=(0, 3)

and the second match has

span=(3, 3)

The same thing is happening for span=(7, 7) in m4 and in your DOTALL code.

It sounds like you want a match only if there's at least one character - repeat with + rather than *:

re.finditer('.+', 'abcn de')

share|improve this answer

answered Jan 3 at 3:01

CertainPerformanceCertainPerformance

97.5k165887

share|improve this answer

share|improve this answer

answered Jan 3 at 3:01

CertainPerformanceCertainPerformance

97.5k165887

answered Jan 3 at 3:01

CertainPerformanceCertainPerformance

97.5k165887

answered Jan 3 at 3:01

CertainPerformanceCertainPerformance

97.5k165887

97.5k165887

add a comment | 

add a comment | 

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