Obviously, you can use the | (pipe?) to represent OR, but is there a way to represent AND as well?
Specifically, I'd like to match paragraphs of text that contain ALL of a certain phrase, but in no particular order.
Use a non-consuming regular expression.
The typical (i.e. Perl/Java) notation is:
(?=expr)
This means "match expr but after that continue matching at the original match-point."
You can do as many of these as you want, and this will be an "and." Example:
(?=match this expression)(?=match this too)(?=oh, and this)
You can even add capture groups inside the non-consuming expressions if you need to save some of the data therein.
You need to use lookahead as some of the other responders have said, but the lookahead has to account for other characters between its target word and the current match position. For example:
(?=.*word1)(?=.*word2)(?=.*word3)
The .* in the first lookahead lets it match however many characters it needs to before it gets to "word1". Then the match position is reset and the second lookahead seeks out "word2". Reset again, and the final part matches "word3"; since it's the last word you're checking for, it isn't necessary that it be in a lookahead, but it doesn't hurt.
In order to match a whole paragraph, you need to anchor the regex at both ends and add a final .* to consume the remaining characters. Using Perl-style notation, that would be:
/^(?=.*word1)(?=.*word2)(?=.*word3).*$/m
The 'm' modifier is for multline mode; it lets the ^ and $ match at paragraph boundaries ("line boundaries" in regex-speak). It's essential in this case that you not use the 's' modifier, which lets the dot metacharacter match newlines as well as all other characters.
Finally, you want to make sure you're matching whole words and not just fragments of longer words, so you need to add word boundaries:
/^(?=.*\bword1\b)(?=.*\bword2\b)(?=.*\bword3\b).*$/m
Look at this example:
We have 2 regexps A and B and we want to match both of them, so in pseudo-code it looks like this:
pattern = "/A AND B/"
It can be written without using the AND operator like this:
pattern = "/NOT (NOT A OR NOT B)/"
in PCRE:
"/(^(^A|^B))/"
regexp_match(pattern,data)
The AND operator is implicit in the RegExp syntax.
The OR operator has instead to be specified with a pipe.
The following RegExp:
var re = /ab/;
means the letter a AND the letter b.
It also works with groups:
var re = /(co)(de)/;
it means the group co AND the group de.
Replacing the (implicit) AND with an OR would require the following lines:
var re = /a|b/;
var re = /(co)|(de)/;
You can do that with a regular expression but probably you'll want to some else. For example use several regexp and combine them in a if clause.
You can enumerate all possible permutations with a standard regexp, like this (matches a, b and c in any order):
(abc)|(bca)|(acb)|(bac)|(cab)|(cba)
However, this makes a very long and probably inefficient regexp, if you have more than couple terms.
If you are using some extended regexp version, like Perl's or Java's, they have better ways to do this. Other answers have suggested using positive lookahead operation.
Is it not possible in your case to do the AND on several matching results? in pseudocode
regexp_match(pattern1, data) && regexp_match(pattern2, data) && ...
Why not use awk?
with awk regex AND, OR matters is so simple
awk '/WORD1/ && /WORD2/ && /WORD3/' myfile
The order is always implied in the structure of the regular expression. To accomplish what you want, you'll have to match the input string multiple times against different expressions.
What you want to do is not possible with a single regexp.
If you use Perl regular expressions, you can use positive lookahead:
For example
(?=[1-9][0-9]{2})[0-9]*[05]\b
would be numbers greater than 100 and divisible by 5
In addition to the accepted answer
I will provide you with some practical examples that will get things more clear to some of You. For example lets say we have those three lines of text:
[12/Oct/2015:00:37:29 +0200] // only this + will get selected
[12/Oct/2015:00:37:x9 +0200]
[12/Oct/2015:00:37:29 +020x]
See demo here DEMO
What we want to do here is to select the + sign but only if it's after two numbers with a space and if it's before four numbers. Those are the only constraints. We would use this regular expression to achieve it:
'~(?<=\d{2} )\+(?=\d{4})~g'
Note if you separate the expression it will give you different results.
Or perhaps you want to select some text between tags... but not the tags! Then you could use:
'~(?<=<p>).*?(?=<\/p>)~g'
for this text:
<p>Hello !</p> <p>I wont select tags! Only text with in</p>
See demo here DEMO
You could pipe your output to another regex. Using grep, you could do this:
grep A | grep B
((yes).*(no))|((no).*(yes))
Will match sentence having both yes and no at the same time, regardless the order in which they appear:
Do i like cookies? **Yes**, i do. But milk - **no**, definitely no.
**No**, you may not have my phone. **Yes**, you may go f yourself.
Will both match, ignoring case.
Use AND outside the regular expression. In PHP lookahead operator did not not seem to work for me, instead I used this
if( preg_match("/^.{3,}$/",$pass1) && !preg_match("/\s{1}/",$pass1))
return true;
else
return false;
The above regex will match if the password length is 3 characters or more and there are no spaces in the password.
Here is a possible "form" for "and" operator:
Take the following regex for an example:
If we want to match words without the "e" character, we could do this:
/\b[^\We]+\b/g
\W means NOT a "word" character.
^\W means a "word" character.
[^\We] means a "word" character, but not an "e".
see it in action: word without e
"and" Operator for Regular Expressions
I think this pattern can be used as an "and" operator for regular expressions.
In general, if:
A = not a
B = not b
then:
[^AB] = not(A or B)
= not(A) and not(B)
= a and b
Difference Set
So, if we want to implement the concept of difference set in regular expressions, we could do this:
a - b = a and not(b)
= a and B
= [^Ab]
I'm quite new to regex. Tried to look at other questions but still can't workout how to resolve my scenario. I want to match string that starts with "AB" but not ABC,or string contains DE but not DEF. For example sDEN23, DET or DE should be matches, AB3 should be matches. I've tried the below so far but it doesn't work as expected. Could someone please help? Many thanks.
Edited: How can this be achieved without using lookahead and lookbehind, as these are not support by Impala?
.*AB?[^C].*|.*DE?[^DEF]
You can use a negative lookahead pattern to avoid matches followed by certain characters:
^(?:AB(?!C)|(?!.*DEF).*DE).*
Demo: https://regex101.com/r/DH1WTf/3
EDIT: Since you've updated the question by replacing the python tag with impala, whose regex engine does not support lookarounds, you can instead use multiple LIKE operators to achieve what you want:
SELECT * FROM table_name WHERE (col LIKE 'AB%' OR col LIKE '%DE%') AND NOT (col LIKE 'ABC%' OR col LIKE '%DEF%')
Try with
(AB)([^C^\n\r])+|(DE)([^F^\n\r])+
Use a negative look ahead for your restrictions, and a match for either of your targets:
^(?!ABC|DEF)(AB|DE).*
See live demo.
I'm trying to build an expression which will match all text EXCLUDING text with prefix 'abc' AND suffix 'def' (text which only has the prefix OR the suffix is ok).
I've tried the following:
^(?!([a][b][c]])).*(?!([d][e][f])$), but it doesn't match text which only has one of the criterias (i.e. abc.xxx fails, as well as xxx.pdf, though they should pass)
I understand the answer is related to 'look behind' but i'm still not quite sure how to achieve this behavior
I've also tried the following:
^(?<!([a][b][c])).*(?!([d][e][f])$), but again, with no luck
^((abc.*\.(?!def))|((?!abc).*\.def))$
I think there can be a simpler solution, but this one will work as you wanted it.
[a][b][c] can be simplified to abc, the same goes for def.
The first part of the pattern matches abc.*\. without def at the end.
The second part matches .*\.def without the prefix abc.
Here is a visual representation of the pattern:
Debuggex Demo
Keep it simple and combine it into a single lookahead to check both conditions:
^(?!abc.*def$).*
I am pretty new to Regular Expression. I want to write a regular expression to get the TO Followed by the rest of it after each new line. I tried to use this but doesn't work properly.
^TO\n?\s?[A-Za-z0-9]\n?[A-Za-z0-9]
It only highlights properly the TO W11 which all are in one line. Highlights only TO from first data and the 3rd data only highlights the first line. Basically it doesn't read the new lines.
Some of my data looks like this:
TO
EXTERNAL
TRAVERSE
TO W11
TO CONTROL
TRAVERSE
I would appreciate if anybody can help me.
Make sure you use a multiline regex:
var options = RegexOptions.MultiLine;
foreach (Match match in Regex.Matches(input, pattern, options))
...
More at: http://msdn.microsoft.com/en-us/library/yd1hzczs(v=vs.110).aspx
It looks like your pattern isn't matching because the start of the string is really a space and not the T character. Also, [A-Za-z0-9] matches only one character, and you want the whole word. I used the + to denote that I want one or more matches of those characters.
(TO\n?\s?[A-Za-z0-9]+)
This regex matches "TO EXTERNAL", "TO W11" and "TO CONTROL". Be sure to use the global modifier so that you get all matches, not just the first one.
how can I write regular expression that dose not contain some string at the end.
in my project,all classes that their names dont end with some string such as "controller" and "map" should inherit from a base class. how can I do this using regular expression ?
but using both
public*.class[a-zA-Z]*(?<!controller|map)$
public*.class*.(?<!controller)$
there isnt any match case!!!
Do a search for all filenames matching this:
(?<!controller|map|anythingelse)$
(Remove the |anythingelse if no other keywords, or append other keywords similarly.)
If you can't use negative lookbehinds (the (?<!..) bit), do a search for filenames that do not match this:
(?:controller|map)$
And if that still doesn't work (might not in some IDEs), remove the ?: part and it probably will - that just makes it a non-capturing group, but the difference here is fairly insignificant.
If you're using something where the full string must match, then you can just prefix either of the above with ^.* to do that.
Update:
In response to this:
but using both
public*.class[a-zA-Z]*(?<!controller|map)$
public*.class*.(?<!controller)$
there isnt any match case!!!
Not quite sure what you're attempting with the public/class stuff there, so try this:
public.*class.*(?<!controller|map)$`
The . is a regex char that means "anything except newline", and the * means zero or more times.
If this isn't what you're after, edit the question with more details.
Depending on your regex implementation, you might be able to use a lookbehind for this task. This would look like
(?<!SomeText)$
This matches any lines NOT having "SomeText" at their end. If you cannot use that, the expression
^(?!.*SomeText$).*$
matches any non-empty lines not ending with "SomeText" as well.
You could write a regex that contains two groups, one consists of one or more characters before controller or map, the other contains controller or map and is optional.
^(.+)(controller|map)?$
With that you may match your string and if there is a group() method in the regex API you use, if group(2) is empty, the string does not contain controller or map.
Check if the name does not match [a-zA-Z]*controller or [a-zA-Z]*map.
finally I did it in this way
public.*class.*[^(controller|map|spec)]$
it worked