I am trying to make a Ultraedit regex which allows me to remove all words of a txt file containing a number.
For example:
test
test2
t2est
te2st
and...
get only
test
A case-insensitive search with Perl regular expression search string \<[a-z]+\d\w*\> finds entire words containing at least 1 digit.
\< ... beginning of a word. \b for any word boundary could be also used.
[a-z]+ ... any letter 1 or more times. You can put additional characters into the square brackets like ÄÖÜäöüß also used in language of text file.
\d ... any digit, i.e. 0-9.
\w* ... any word character 0 or more times. Any word character means all word characters according to Unicode table which includes language dependent word characters, all digits and the underscore.
\> ... end of a word. \b for any word boundary could be also used.
A case-insensitive search with UltraEdit regular expression search string [a-z]+[0-9][a-z0-9_]++ finds also entire words containing at least 1 digit if additionally the find option Match whole word is also checked.
[a-z]+ ... any letter 1 or more times. You can put additional characters into the square brackets used in language of text file.
[0-9] ... any digit.
[a-z0-9_]++ ... any letter, digit or underscore 0 or more times.
The UltraEdit regexp search string [a-z]+[0-9][a-z0-9_]++ in Unix/Perl syntax would be [a-z]+[0-9][a-z0-9_]* which could be also used with find option Match whole word checked instead of the Perl regexp search.
Related
I need a regular expression able to match everything but a string starting with a specific pattern (specifically index.php and what follows, like index.php?id=2342343).
Regex: match everything but:
a string starting with a specific pattern (e.g. any - empty, too - string not starting with foo):
Lookahead-based solution for NFAs:
^(?!foo).*$
^(?!foo)
Negated character class based solution for regex engines not supporting lookarounds:
^(([^f].{2}|.[^o].|.{2}[^o]).*|.{0,2})$
^([^f].{2}|.[^o].|.{2}[^o])|^.{0,2}$
a string ending with a specific pattern (say, no world. at the end):
Lookbehind-based solution:
(?<!world\.)$
^.*(?<!world\.)$
Lookahead solution:
^(?!.*world\.$).*
^(?!.*world\.$)
POSIX workaround:
^(.*([^w].{5}|.[^o].{4}|.{2}[^r].{3}|.{3}[^l].{2}|.{4}[^d].|.{5}[^.])|.{0,5})$
([^w].{5}|.[^o].{4}|.{2}[^r].{3}|.{3}[^l].{2}|.{4}[^d].|.{5}[^.]$|^.{0,5})$
a string containing specific text (say, not match a string having foo):
Lookaround-based solution:
^(?!.*foo)
^(?!.*foo).*$
POSIX workaround:
Use the online regex generator at www.formauri.es/personal/pgimeno/misc/non-match-regex
a string containing specific character (say, avoid matching a string having a | symbol):
^[^|]*$
a string equal to some string (say, not equal to foo):
Lookaround-based:
^(?!foo$)
^(?!foo$).*$
POSIX:
^(.{0,2}|.{4,}|[^f]..|.[^o].|..[^o])$
a sequence of characters:
PCRE (match any text but cat): /cat(*SKIP)(*FAIL)|[^c]*(?:c(?!at)[^c]*)*/i or /cat(*SKIP)(*FAIL)|(?:(?!cat).)+/is
Other engines allowing lookarounds: (cat)|[^c]*(?:c(?!at)[^c]*)* (or (?s)(cat)|(?:(?!cat).)*, or (cat)|[^c]+(?:c(?!at)[^c]*)*|(?:c(?!at)[^c]*)+[^c]*) and then check with language means: if Group 1 matched, it is not what we need, else, grab the match value if not empty
a certain single character or a set of characters:
Use a negated character class: [^a-z]+ (any char other than a lowercase ASCII letter)
Matching any char(s) but |: [^|]+
Demo note: the newline \n is used inside negated character classes in demos to avoid match overflow to the neighboring line(s). They are not necessary when testing individual strings.
Anchor note: In many languages, use \A to define the unambiguous start of string, and \z (in Python, it is \Z, in JavaScript, $ is OK) to define the very end of the string.
Dot note: In many flavors (but not POSIX, TRE, TCL), . matches any char but a newline char. Make sure you use a corresponding DOTALL modifier (/s in PCRE/Boost/.NET/Python/Java and /m in Ruby) for the . to match any char including a newline.
Backslash note: In languages where you have to declare patterns with C strings allowing escape sequences (like \n for a newline), you need to double the backslashes escaping special characters so that the engine could treat them as literal characters (e.g. in Java, world\. will be declared as "world\\.", or use a character class: "world[.]"). Use raw string literals (Python r'\bworld\b'), C# verbatim string literals #"world\.", or slashy strings/regex literal notations like /world\./.
You could use a negative lookahead from the start, e.g., ^(?!foo).*$ shouldn't match anything starting with foo.
You can put a ^ in the beginning of a character set to match anything but those characters.
[^=]*
will match everything but =
Just match /^index\.php/, and then reject whatever matches it.
In Python:
>>> import re
>>> p='^(?!index\.php\?[0-9]+).*$'
>>> s1='index.php?12345'
>>> re.match(p,s1)
>>> s2='index.html?12345'
>>> re.match(p,s2)
<_sre.SRE_Match object at 0xb7d65fa8>
Came across this thread after a long search. I had this problem for multiple searches and replace of some occurrences. But the pattern I used was matching till the end. Example below
import re
text = "start![image]xxx(xx.png) yyy xx![image]xxx(xxx.png) end"
replaced_text = re.sub(r'!\[image\](.*)\(.*\.png\)', '*', text)
print(replaced_text)
gave
start* end
Basically, the regex was matching from the first ![image] to the last .png, swallowing the middle yyy
Used the method posted above https://stackoverflow.com/a/17761124/429476 by Firish to break the match between the occurrence. Here the space is not matched; as the words are separated by space.
replaced_text = re.sub(r'!\[image\]([^ ]*)\([^ ]*\.png\)', '*', text)
and got what I wanted
start* yyy xx* end
The Lua manual in section 6.4.1 on Lua Patterns states
A character class is used to represent a set of characters. The
following combinations are allowed in describing a character class:
x: (where x is not one of the magic characters ^$()%.[]*+-?) represents the character x itself.
.: (a dot) represents all characters.
%a: represents all letters.
%c: represents all control characters.
%d: represents all digits.
%g: represents all printable characters except space.
%l: represents all lowercase letters.
%p: represents all punctuation characters.
%s: represents all space characters.
%u: represents all uppercase letters.
%w: represents all alphanumeric characters.
%x: represents all hexadecimal digits.
%x: (where x is any non-alphanumeric character) represents the character x. This is the standard way to escape the magic characters.
Any non-alphanumeric character (including all punctuation characters,
even the non-magical) can be preceded by a % when used to represent
itself in a pattern.
[set]: represents the class which is the union of all characters in set. A range of characters can be specified by separating the end
characters of the range, in ascending order, with a -. All classes
%x described above can also be used as components in set. All other
characters in set represent themselves. For example, [%w_] (or
[_%w]) represents all alphanumeric characters plus the underscore,
[0-7] represents the octal digits, and [0-7%l%-] represents the
octal digits plus the lowercase letters plus the - character.
You can put a closing square bracket in a set by positioning it as the
first character in the set. You can put a hyphen in a set by
positioning it as the first or the last character in the set. (You can
also use an escape for both cases.)
The interaction between ranges and classes is not defined. Therefore, patterns like [%a-z] or [a-%%] have no meaning.
[^set]: represents the complement of set, where set is interpreted
as above.
For all classes represented by single letters (%a, %c, etc.), the
corresponding uppercase letter represents the complement of the class.
For instance, %S represents all non-space characters.
The definitions of letter, space, and other character groups depend on
the current locale. In particular, the class [a-z] may not be
equivalent to %l.
(Highlighting and some formatting added by me)
So, since the "interaction between ranges and classes is not defined.", how do you create a character class set that starts and/or ends with a (magic) character that needs to be escaped?
For example,
[%%-c]
does not define a character class that ranges from % to c and includes all characters in-between but a set that consists only of the three characters %, -, and c.
The interaction between ranges and classes is not defined.
Obviously, this is not a hard and fast rule (of regex character sets in general) but a Lua implementation decision. While using shorthand characters in character sets/ranges work in some (most) regex flavors, it does not in all (like in Python's re module, demo).
However, the second example is misleading:
Therefore, patterns like [%a-z] or [a-%%] have no meaning.
While the first example is fine since %a is a shorthand class (that represents all letters) in a set, [%a-z] is undefined and will return nil if matched against a string.
Escaped range characters in a [set]
In the second example, [a-%%], %% simply defines an escaped % sign and not a shorthand character class. The superficial problem is, the range is defined upsidedown, from high to low (in reference to the US ASCII value of the characters a 61 and % 37), e.g like an erroneous Lua pattern like [f-a]. If the set is defined in reverse order it seems to work: [%%-a] but all it does is matching the three individual characters instead of the range of characters between % and a; credit cyclaminist).
This could be considered a bug and, indeed, means it is not possible to create a range of characters in a [set] if one of the defining range characters need to be escaped.
Possible Solution
Start the character range from the next character that does not need to be escaped - and then add the remaining escaped characters individually, e.g.
[%%&-a]
Sample:
for w in string.gmatch("%&*()-0Aa", "[%%&-a]") do
print(w)
end
This is the answer I have found. Still, maybe somebody else has something better.
I have two regular expressions: ^(\\p{L}|[0-9]|_)+$ and #[^[:punct:][:space:]]+ (the first is used in Java, the second on iOS). I want to combine these into one expression, to match either one or the other in iOS.
The first one is for a username so I also need to add a # character to the start of that one. What would that look like?
The ^(\\p{L}|[0-9]|_)+$ pattern in Java matches the same way as in ICU library used in iOS (they are very similar): a whole string consisting of 1 or more Unicode letters, ASCII digits or _. It is poorly written as the alternation group is quantified and that is much less efficient than a character class based solution, ^[\\p{L}0-9_]+$.
The #[^[:punct:][:space:]]+ pattern matches a # followed with 1 or more chars other than punctuation/symbols and whitespace chars (that is, 1 or more letters or digits, or alphanumeric chars).
What you seek can be writtern as
#[\\p{L}0-9_]+|[^[:punct:][:space:]]+
or
#[\\p{L}0-9_]+|#[[:alnum:]]+
or if you want to limit to ASCII digits and not match Unicode digits:
#[\\p{L}0-9_]+|#[\\p{L}0-9]+
It matches
# - a # symbol
[\\p{L}0-9_]+ - 1 or more Unicode letters, ASCII diigts, _
| - or
# - a # char
[[:alnum:]]+ - 1 or more letters or digits.
[^[:punct:][:space:]]+ - any 1+ chars other than punctuation/symbols and whitespace.
Basically, all these expressions match strings like this.
If you want to match #SomeThing_123 in full, just use [##]\\w+, a # or # and then 1 or more letters, digits or _, or to only allow ASCII digits, [##][\\p{L}0-9_]+.
A word boundary may be required at the end of the pattern, [##][\\p{L}0-9_]+\\b.
I have following regex handy to match all the lines containing console.log() or alert() function in any javascript file opened in the editor supporting PCRE.
^.*\b(console\.log|alert)\b.*$
But I encounter many files containing window.alert() lines for alerting important messages, I don't want to remove/replace them.
So the question how to regex-match (single line regex without need to run frequently) all the lines containing console.log() and alert() but not containing word window. Also how to escape round brackets(parenthesis) which are unescapable by \, to make them part of string literal ?
I tried following regex but in vain:
^.*\b(console\.log|alert)((?!window).)*\b.*$
You should use a negative lookhead, like this:
^(?!.*window\.).*\b(console\.log|alert)\b.*$
The negative lookhead will assert that it is impossible to match if the string window. is present.
Regex Demo
As for the parenthesis, you can escape them with backslashes, but because you have a word boundary character, it will not match if you put the escaped parenthesis, because they are not word characters.
The metacharacter \b is an anchor like the caret and the dollar sign.
It matches at a position that is called a "word boundary". This match
is zero-length.
There are three different positions that qualify as word boundaries:
Before the first character in the string, if the first character is a
word character.
After the last character in the string, if the last
character is a word character.
Between two characters in the string,
where one is a word character and the other is not a word character.
Just came across this pattern, which I really don't understand:
^[%w-.]+$
And could you give me some examples to match this expression?
Valid in Lua, where %w is (almost) the equivalent of \w in other languages
^[%w-.]+$ means match a string that is entirely composed of alphanumeric characters (letters and digits), dashes or dots.
Explanation
The ^ anchor asserts that we are at the beginning of the string
The character class [%w-.] matches one character that is a letter or digit (the meaning of %w), or a dash, or a period. This would be the equivalent of [\w-.] in JavaScript
The + quantifier matches such a character one or more times
The $ anchor asserts that we are at the end of the string
Reference
Lua Patterns
Actually it will match nothing. Because there is an error: w- this is a start of a text range and it is out of order. So it should be %w\- instead.
^[%w\-.]+$
Means:
^ assert position at start of the string
[%w\-.]+ match a single character present in the list below
+ Quantifier: Between one and unlimited times, as many times as possible, giving back as needed [greedy]
%w a single character in the list %w literally (case sensitive)
\- matches the character - literally
. the literal character .
$ assert position at end of the string
Edit
As the OP changed the question and the tags this answer no longer fits as a proper answer. It is POSIX based answer.
As #zx81 comment:
%w is \w in Lua which means any alphanumeric characters plus "_"