preg_match_all negative lookahead and negative lookbehind
I have this pattern which starts with (?<![d.,]) and ends with (?![d.,%]| %)
Why does it match 16 ?
I would expect it not to match anything in this string
$pattern = '/(?<![d.,])-?d{1,3}(?:(?:[. ]d{3})*|d*)(?:b|[^.,%]|[,]d{1,2})-?(?![d.,%]| %)/';
$value = 'dag 08-16 flex pakke';
echo "pattern: $patternnvalue: $valuen";
preg_match_all($pattern, $value, $matches);
print_r($matches);
php regex
asked Jan 18 at 12:38
clarkkclarkk
7,67845144232
add a comment |
I have this pattern which starts with (?<![d.,]) and ends with (?![d.,%]| %)
Why does it match 16 ?
I would expect it not to match anything in this string
$pattern = '/(?<![d.,])-?d{1,3}(?:(?:[. ]d{3})*|d*)(?:b|[^.,%]|[,]d{1,2})-?(?![d.,%]| %)/';
$value = 'dag 08-16 flex pakke';
echo "pattern: $patternnvalue: $valuen";
preg_match_all($pattern, $value, $matches);
print_r($matches);
php regex
asked Jan 18 at 12:38
clarkkclarkk
7,67845144232
2
Try regex101.com/r/KDgbjl/1, but if you explain your requirements, it could help to come up with a cleaner regex.
– Wiktor Stribiżew
Jan 18 at 12:42
Comment your regex and make it multiline with the/xflag.
– mario
Jan 18 at 12:47
Maybe you need to include-in the negative lookbehind?(?<![d.,-])
– revo
Jan 18 at 13:06
@WiktorStribiżew, create an answer.. your lookbehind helped me on the right path :)
– clarkk
Jan 18 at 13:17
Please also consider upvoting my answer if it turned out helpful to you.
– Wiktor Stribiżew
yesterday
add a comment |
I have this pattern which starts with (?<![d.,]) and ends with (?![d.,%]| %)
Why does it match 16 ?
I would expect it not to match anything in this string
$pattern = '/(?<![d.,])-?d{1,3}(?:(?:[. ]d{3})*|d*)(?:b|[^.,%]|[,]d{1,2})-?(?![d.,%]| %)/';
$value = 'dag 08-16 flex pakke';
echo "pattern: $patternnvalue: $valuen";
preg_match_all($pattern, $value, $matches);
print_r($matches);
php regex
asked Jan 18 at 12:38
clarkkclarkk
7,67845144232
I have this pattern which starts with (?<![d.,]) and ends with (?![d.,%]| %)
Why does it match 16 ?
I would expect it not to match anything in this string
$pattern = '/(?<![d.,])-?d{1,3}(?:(?:[. ]d{3})*|d*)(?:b|[^.,%]|[,]d{1,2})-?(?![d.,%]| %)/';
$value = 'dag 08-16 flex pakke';
echo "pattern: $patternnvalue: $valuen";
preg_match_all($pattern, $value, $matches);
print_r($matches);
php regex
php regex
asked Jan 18 at 12:38
clarkkclarkk
7,67845144232
asked Jan 18 at 12:38
clarkkclarkk
7,67845144232
asked Jan 18 at 12:38
clarkkclarkk
7,67845144232
asked Jan 18 at 12:38
clarkkclarkk
7,67845144232
asked Jan 18 at 12:38
clarkkclarkk
7,67845144232
7,67845144232
2
Try regex101.com/r/KDgbjl/1, but if you explain your requirements, it could help to come up with a cleaner regex.
– Wiktor Stribiżew
Jan 18 at 12:42
Comment your regex and make it multiline with the/xflag.
– mario
Jan 18 at 12:47
Maybe you need to include-in the negative lookbehind?(?<![d.,-])
– revo
Jan 18 at 13:06
@WiktorStribiżew, create an answer.. your lookbehind helped me on the right path :)
– clarkk
Jan 18 at 13:17
Please also consider upvoting my answer if it turned out helpful to you.
– Wiktor Stribiżew
yesterday
add a comment |
2
Try regex101.com/r/KDgbjl/1, but if you explain your requirements, it could help to come up with a cleaner regex.
– Wiktor Stribiżew
Jan 18 at 12:42
Comment your regex and make it multiline with the/xflag.
– mario
Jan 18 at 12:47
Maybe you need to include-in the negative lookbehind?(?<![d.,-])
– revo
Jan 18 at 13:06
@WiktorStribiżew, create an answer.. your lookbehind helped me on the right path :)
– clarkk
Jan 18 at 13:17
Please also consider upvoting my answer if it turned out helpful to you.
– Wiktor Stribiżew
yesterday
2
2
Try regex101.com/r/KDgbjl/1, but if you explain your requirements, it could help to come up with a cleaner regex.
– Wiktor Stribiżew
Jan 18 at 12:42
Try regex101.com/r/KDgbjl/1, but if you explain your requirements, it could help to come up with a cleaner regex.
– Wiktor Stribiżew
Jan 18 at 12:42
Comment your regex and make it multiline with the
/x flag.– mario
Jan 18 at 12:47
Comment your regex and make it multiline with the
/x flag.– mario
Jan 18 at 12:47
Maybe you need to include
- in the negative lookbehind? (?<![d.,-])– revo
Jan 18 at 13:06
Maybe you need to include
- in the negative lookbehind? (?<![d.,-])– revo
Jan 18 at 13:06
@WiktorStribiżew, create an answer.. your lookbehind helped me on the right path :)
– clarkk
Jan 18 at 13:17
@WiktorStribiżew, create an answer.. your lookbehind helped me on the right path :)
– clarkk
Jan 18 at 13:17
Please also consider upvoting my answer if it turned out helpful to you.
– Wiktor Stribiżew
yesterday
Please also consider upvoting my answer if it turned out helpful to you.
– Wiktor Stribiżew
yesterday
add a comment |
1 Answer
1
active
oldest
votes
Your lookarounds stand next to optional patterns, -?. Thus, whenever the lookarounds fail, backtracking occurs, and the unwelcome matches occur.
To avoid this, account for the optional pattern inside the lookaround patterns.
/-?(?<![d.,]-|[d.,])d{1,3}(?:(?:[. ]d{3})*|d*)(?:b|[^.,%]|,d{1,2})(?!-?(?:[d.,%]| %))-?/
^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^
See the regex demo
answered Jan 18 at 13:21
Wiktor StribiżewWiktor Stribiżew
312k16132207
add a comment |
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1 Answer
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active
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Your lookarounds stand next to optional patterns, -?. Thus, whenever the lookarounds fail, backtracking occurs, and the unwelcome matches occur.
To avoid this, account for the optional pattern inside the lookaround patterns.
/-?(?<![d.,]-|[d.,])d{1,3}(?:(?:[. ]d{3})*|d*)(?:b|[^.,%]|,d{1,2})(?!-?(?:[d.,%]| %))-?/
^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^
See the regex demo
answered Jan 18 at 13:21
Wiktor StribiżewWiktor Stribiżew
312k16132207
add a comment |
Your lookarounds stand next to optional patterns, -?. Thus, whenever the lookarounds fail, backtracking occurs, and the unwelcome matches occur.
To avoid this, account for the optional pattern inside the lookaround patterns.
/-?(?<![d.,]-|[d.,])d{1,3}(?:(?:[. ]d{3})*|d*)(?:b|[^.,%]|,d{1,2})(?!-?(?:[d.,%]| %))-?/
^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^
See the regex demo
answered Jan 18 at 13:21
Wiktor StribiżewWiktor Stribiżew
312k16132207
add a comment |
Your lookarounds stand next to optional patterns, -?. Thus, whenever the lookarounds fail, backtracking occurs, and the unwelcome matches occur.
To avoid this, account for the optional pattern inside the lookaround patterns.
/-?(?<![d.,]-|[d.,])d{1,3}(?:(?:[. ]d{3})*|d*)(?:b|[^.,%]|,d{1,2})(?!-?(?:[d.,%]| %))-?/
^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^
See the regex demo
answered Jan 18 at 13:21
Wiktor StribiżewWiktor Stribiżew
312k16132207
Your lookarounds stand next to optional patterns, -?. Thus, whenever the lookarounds fail, backtracking occurs, and the unwelcome matches occur.
To avoid this, account for the optional pattern inside the lookaround patterns.
/-?(?<![d.,]-|[d.,])d{1,3}(?:(?:[. ]d{3})*|d*)(?:b|[^.,%]|,d{1,2})(?!-?(?:[d.,%]| %))-?/
^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^
See the regex demo
answered Jan 18 at 13:21
Wiktor StribiżewWiktor Stribiżew
312k16132207
answered Jan 18 at 13:21
Wiktor StribiżewWiktor Stribiżew
312k16132207
answered Jan 18 at 13:21
Wiktor StribiżewWiktor Stribiżew
312k16132207
answered Jan 18 at 13:21
Wiktor StribiżewWiktor Stribiżew
312k16132207
312k16132207
add a comment |
add a comment |
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2
Try regex101.com/r/KDgbjl/1, but if you explain your requirements, it could help to come up with a cleaner regex.
– Wiktor Stribiżew
Jan 18 at 12:42
Comment your regex and make it multiline with the
/xflag.– mario
Jan 18 at 12:47
Maybe you need to include
-in the negative lookbehind?(?<![d.,-])– revo
Jan 18 at 13:06
@WiktorStribiżew, create an answer.. your lookbehind helped me on the right path :)
– clarkk
Jan 18 at 13:17
Please also consider upvoting my answer if it turned out helpful to you.
– Wiktor Stribiżew
yesterday