Does a dot have to be escaped in a character class (square brackets) of a regular expression?
63
A dot . in a regular expression matches any single character. In order for regex to match a dot, the dot has to be escaped: .
It has been pointed out to me that inside square brackets a dot does not have to be escaped. For example, the expression:
[.]{3} would match ... string.
Doesn't it, really? And if so, is it true for all regex standards?
regex standards standards-compliance square-bracket
edited May 23 '17 at 12:25
Community♦
11
asked Nov 14 '13 at 11:04
DariuszDariusz
15.6k54783
|
show 1 more comment
63
A dot . in a regular expression matches any single character. In order for regex to match a dot, the dot has to be escaped: .
It has been pointed out to me that inside square brackets a dot does not have to be escaped. For example, the expression:
[.]{3} would match ... string.
Doesn't it, really? And if so, is it true for all regex standards?
regex standards standards-compliance square-bracket
edited May 23 '17 at 12:25
Community♦
11
asked Nov 14 '13 at 11:04
DariuszDariusz
15.6k54783
Yes that is true that DOT (and most other special characters) don't need to be escaped in character class.
– anubhava
Nov 14 '13 at 11:05
2
There is no "standard" for regular expression syntax.
– BoltClock♦
Nov 14 '13 at 11:06
2
@BoltClock there are some: posix, posix extended, perl. See en.wikipedia.org/wiki/Regular_expression#Standards
– Dariusz
Nov 14 '13 at 12:31
1
@Dariusz were you the one who down voted me because you thought I was wrong? if so, I want my 2 points back :)
– Paul Samsotha
Nov 14 '13 at 12:58
@peeskillet yes I was, I stand corrected. Thx and sorry.
– Dariusz
Nov 14 '13 at 13:07
|
show 1 more comment
63
63
63
10
A dot . in a regular expression matches any single character. In order for regex to match a dot, the dot has to be escaped: .
It has been pointed out to me that inside square brackets a dot does not have to be escaped. For example, the expression:
[.]{3} would match ... string.
Doesn't it, really? And if so, is it true for all regex standards?
regex standards standards-compliance square-bracket
edited May 23 '17 at 12:25
Community♦
11
asked Nov 14 '13 at 11:04
DariuszDariusz
15.6k54783
A dot . in a regular expression matches any single character. In order for regex to match a dot, the dot has to be escaped: .
It has been pointed out to me that inside square brackets a dot does not have to be escaped. For example, the expression:
[.]{3} would match ... string.
Doesn't it, really? And if so, is it true for all regex standards?
regex standards standards-compliance square-bracket
regex standards standards-compliance square-bracket
edited May 23 '17 at 12:25
Community♦
11
asked Nov 14 '13 at 11:04
DariuszDariusz
15.6k54783
edited May 23 '17 at 12:25
Community♦
11
asked Nov 14 '13 at 11:04
DariuszDariusz
15.6k54783
edited May 23 '17 at 12:25
Community♦
11
edited May 23 '17 at 12:25
Community♦
11
edited May 23 '17 at 12:25
Community♦
11
11
asked Nov 14 '13 at 11:04
DariuszDariusz
15.6k54783
asked Nov 14 '13 at 11:04
DariuszDariusz
15.6k54783
asked Nov 14 '13 at 11:04
DariuszDariusz
15.6k54783
15.6k54783
Yes that is true that DOT (and most other special characters) don't need to be escaped in character class.
– anubhava
Nov 14 '13 at 11:05
2
There is no "standard" for regular expression syntax.
– BoltClock♦
Nov 14 '13 at 11:06
2
@BoltClock there are some: posix, posix extended, perl. See en.wikipedia.org/wiki/Regular_expression#Standards
– Dariusz
Nov 14 '13 at 12:31
1
@Dariusz were you the one who down voted me because you thought I was wrong? if so, I want my 2 points back :)
– Paul Samsotha
Nov 14 '13 at 12:58
@peeskillet yes I was, I stand corrected. Thx and sorry.
– Dariusz
Nov 14 '13 at 13:07
|
show 1 more comment
Yes that is true that DOT (and most other special characters) don't need to be escaped in character class.
– anubhava
Nov 14 '13 at 11:05
2
There is no "standard" for regular expression syntax.
– BoltClock♦
Nov 14 '13 at 11:06
2
@BoltClock there are some: posix, posix extended, perl. See en.wikipedia.org/wiki/Regular_expression#Standards
– Dariusz
Nov 14 '13 at 12:31
1
@Dariusz were you the one who down voted me because you thought I was wrong? if so, I want my 2 points back :)
– Paul Samsotha
Nov 14 '13 at 12:58
@peeskillet yes I was, I stand corrected. Thx and sorry.
– Dariusz
Nov 14 '13 at 13:07
Yes that is true that DOT (and most other special characters) don't need to be escaped in character class.
– anubhava
Nov 14 '13 at 11:05
Yes that is true that DOT (and most other special characters) don't need to be escaped in character class.
– anubhava
Nov 14 '13 at 11:05
2
2
There is no "standard" for regular expression syntax.
– BoltClock♦
Nov 14 '13 at 11:06
There is no "standard" for regular expression syntax.
– BoltClock♦
Nov 14 '13 at 11:06
2
2
@BoltClock there are some: posix, posix extended, perl. See en.wikipedia.org/wiki/Regular_expression#Standards
– Dariusz
Nov 14 '13 at 12:31
@BoltClock there are some: posix, posix extended, perl. See en.wikipedia.org/wiki/Regular_expression#Standards
– Dariusz
Nov 14 '13 at 12:31
1
1
@Dariusz were you the one who down voted me because you thought I was wrong? if so, I want my 2 points back :)
– Paul Samsotha
Nov 14 '13 at 12:58
@Dariusz were you the one who down voted me because you thought I was wrong? if so, I want my 2 points back :)
– Paul Samsotha
Nov 14 '13 at 12:58
@peeskillet yes I was, I stand corrected. Thx and sorry.
– Dariusz
Nov 14 '13 at 13:07
@peeskillet yes I was, I stand corrected. Thx and sorry.
– Dariusz
Nov 14 '13 at 13:07
|
show 1 more comment
1 Answer
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88
In a character class (square brackets) any character except ^, -, ] or is a literal.
This website is a brilliant reference and has lots of info on the nuances of different regex flavours.
http://www.regular-expressions.info/refcharclass.html
edited Dec 27 '16 at 17:56
MrWhite
12.9k33262
answered Nov 14 '13 at 11:18
lilactiger89lilactiger89
1,065813
2
It really depends on how the language handles it, but for most languages this is true.
– Patrick Oscity
Nov 14 '13 at 11:26
26
-is also literal if it's the last value
– Pedro Lobito
May 10 '16 at 12:38
In ICU and Java regexps, both the[and]must be escaped inside a character class (and{and}must be escaped outside the character class).
– Wiktor Stribiżew
Oct 11 '16 at 7:03
9
And ^ is literal if it's not the first character
– Nigel Peck
Dec 17 '16 at 2:52
1
If $ looks like a variable, it also needs to be escaped. E.g.: [$.]
– W3Coder
Mar 31 '17 at 13:55
|
show 3 more comments
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1 Answer
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88
In a character class (square brackets) any character except ^, -, ] or is a literal.
This website is a brilliant reference and has lots of info on the nuances of different regex flavours.
http://www.regular-expressions.info/refcharclass.html
edited Dec 27 '16 at 17:56
MrWhite
12.9k33262
answered Nov 14 '13 at 11:18
lilactiger89lilactiger89
1,065813
2
It really depends on how the language handles it, but for most languages this is true.
– Patrick Oscity
Nov 14 '13 at 11:26
26
-is also literal if it's the last value
– Pedro Lobito
May 10 '16 at 12:38
In ICU and Java regexps, both the[and]must be escaped inside a character class (and{and}must be escaped outside the character class).
– Wiktor Stribiżew
Oct 11 '16 at 7:03
9
And ^ is literal if it's not the first character
– Nigel Peck
Dec 17 '16 at 2:52
1
If $ looks like a variable, it also needs to be escaped. E.g.: [$.]
– W3Coder
Mar 31 '17 at 13:55
|
show 3 more comments
88
In a character class (square brackets) any character except ^, -, ] or is a literal.
This website is a brilliant reference and has lots of info on the nuances of different regex flavours.
http://www.regular-expressions.info/refcharclass.html
edited Dec 27 '16 at 17:56
MrWhite
12.9k33262
answered Nov 14 '13 at 11:18
lilactiger89lilactiger89
1,065813
2
It really depends on how the language handles it, but for most languages this is true.
– Patrick Oscity
Nov 14 '13 at 11:26
26
-is also literal if it's the last value
– Pedro Lobito
May 10 '16 at 12:38
In ICU and Java regexps, both the[and]must be escaped inside a character class (and{and}must be escaped outside the character class).
– Wiktor Stribiżew
Oct 11 '16 at 7:03
9
And ^ is literal if it's not the first character
– Nigel Peck
Dec 17 '16 at 2:52
1
If $ looks like a variable, it also needs to be escaped. E.g.: [$.]
– W3Coder
Mar 31 '17 at 13:55
|
show 3 more comments
88
88
88
In a character class (square brackets) any character except ^, -, ] or is a literal.
This website is a brilliant reference and has lots of info on the nuances of different regex flavours.
http://www.regular-expressions.info/refcharclass.html
edited Dec 27 '16 at 17:56
MrWhite
12.9k33262
answered Nov 14 '13 at 11:18
lilactiger89lilactiger89
1,065813
In a character class (square brackets) any character except ^, -, ] or is a literal.
This website is a brilliant reference and has lots of info on the nuances of different regex flavours.
http://www.regular-expressions.info/refcharclass.html
edited Dec 27 '16 at 17:56
MrWhite
12.9k33262
answered Nov 14 '13 at 11:18
lilactiger89lilactiger89
1,065813
edited Dec 27 '16 at 17:56
MrWhite
12.9k33262
edited Dec 27 '16 at 17:56
MrWhite
12.9k33262
edited Dec 27 '16 at 17:56
MrWhite
12.9k33262
12.9k33262
answered Nov 14 '13 at 11:18
lilactiger89lilactiger89
1,065813
answered Nov 14 '13 at 11:18
lilactiger89lilactiger89
1,065813
answered Nov 14 '13 at 11:18
lilactiger89lilactiger89
1,065813
1,065813
2
It really depends on how the language handles it, but for most languages this is true.
– Patrick Oscity
Nov 14 '13 at 11:26
26
-is also literal if it's the last value
– Pedro Lobito
May 10 '16 at 12:38
In ICU and Java regexps, both the[and]must be escaped inside a character class (and{and}must be escaped outside the character class).
– Wiktor Stribiżew
Oct 11 '16 at 7:03
9
And ^ is literal if it's not the first character
– Nigel Peck
Dec 17 '16 at 2:52
1
If $ looks like a variable, it also needs to be escaped. E.g.: [$.]
– W3Coder
Mar 31 '17 at 13:55
|
show 3 more comments
2
It really depends on how the language handles it, but for most languages this is true.
– Patrick Oscity
Nov 14 '13 at 11:26
26
-is also literal if it's the last value
– Pedro Lobito
May 10 '16 at 12:38
In ICU and Java regexps, both the[and]must be escaped inside a character class (and{and}must be escaped outside the character class).
– Wiktor Stribiżew
Oct 11 '16 at 7:03
9
And ^ is literal if it's not the first character
– Nigel Peck
Dec 17 '16 at 2:52
1
If $ looks like a variable, it also needs to be escaped. E.g.: [$.]
– W3Coder
Mar 31 '17 at 13:55
2
2
It really depends on how the language handles it, but for most languages this is true.
– Patrick Oscity
Nov 14 '13 at 11:26
It really depends on how the language handles it, but for most languages this is true.
– Patrick Oscity
Nov 14 '13 at 11:26
26
26
- is also literal if it's the last value– Pedro Lobito
May 10 '16 at 12:38
- is also literal if it's the last value– Pedro Lobito
May 10 '16 at 12:38
In ICU and Java regexps, both the
[ and ] must be escaped inside a character class (and { and } must be escaped outside the character class).– Wiktor Stribiżew
Oct 11 '16 at 7:03
In ICU and Java regexps, both the
[ and ] must be escaped inside a character class (and { and } must be escaped outside the character class).– Wiktor Stribiżew
Oct 11 '16 at 7:03
9
9
And ^ is literal if it's not the first character
– Nigel Peck
Dec 17 '16 at 2:52
And ^ is literal if it's not the first character
– Nigel Peck
Dec 17 '16 at 2:52
1
1
If $ looks like a variable, it also needs to be escaped. E.g.: [$.]
– W3Coder
Mar 31 '17 at 13:55
If $ looks like a variable, it also needs to be escaped. E.g.: [$.]
– W3Coder
Mar 31 '17 at 13:55
|
show 3 more comments
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Yes that is true that DOT (and most other special characters) don't need to be escaped in character class.
– anubhava
Nov 14 '13 at 11:05
2
There is no "standard" for regular expression syntax.
– BoltClock♦
Nov 14 '13 at 11:06
2
@BoltClock there are some: posix, posix extended, perl. See en.wikipedia.org/wiki/Regular_expression#Standards
– Dariusz
Nov 14 '13 at 12:31
1
@Dariusz were you the one who down voted me because you thought I was wrong? if so, I want my 2 points back :)
– Paul Samsotha
Nov 14 '13 at 12:58
@peeskillet yes I was, I stand corrected. Thx and sorry.
– Dariusz
Nov 14 '13 at 13:07