I've got a regular expression like this
something (.*) someotherthing
How do I use a Regex object to match the entire expression and get the value of the capture?
Here is an example of what I think you are asking for:
Match m = Regex.Match( "something some stuff in the middle someotherthing",
"something (.*) someotherthing" );
if ( m.Success )
Console.WriteLine( "groups={0}, entire match={1}, first group={2}",
m.Groups.Count, m.Groups[0].Value,
m.Groups[1].Value );
Where you can use $1 to get that group, you can use $0 to get the entire expression.
This works in most regex variants (may be \0 or %0 or whatever), not just C#.
Similarly, the Match.Groups property should work with 0 as an argument to return the whole match, otherwise Capture.Value looks like it contains the match.
Also worth noting, to ensure your test string matches the entire expression, it's generally a good idea to prefix with ^ and suffix with $ which are zero-width position anchors for start and end of string. (Also start/end of line in multiline mode.)
Regex.Match
http://msdn.microsoft.com/en-us/library/twcw2f1c.aspx
Related
I need a regex that will only find matches where the entire string matches my query.
For instance if I do a search for movies with the name "Red October" I only want to match on that exact title (case insensitive) but not match titles like "The Hunt For Red October". Not quite sure I know how to do this. Anyone know?
Thanks!
Try the following regular expression:
^Red October$
By default, regular expressions are case sensitive. The ^ marks the start of the matching text and $ the end.
Generally, and with default settings, ^ and $ anchors are a good way of ensuring that a regex matches an entire string.
A few caveats, though:
If you have alternation in your regex, be sure to enclose your regex in a non-capturing group before surrounding it with ^ and $:
^foo|bar$
is of course different from
^(?:foo|bar)$
Also, ^ and $ can take on a different meaning (start/end of line instead of start/end of string) if certain options are set. In text editors that support regular expressions, this is usually the default behaviour. In some languages, especially Ruby, this behaviour cannot even be switched off.
Therefore there is another set of anchors that are guaranteed to only match at the start/end of the entire string:
\A matches at the start of the string.
\Z matches at the end of the string or before a final line break.
\z matches at the very end of the string.
But not all languages support these anchors, most notably JavaScript.
I know that this may be a little late to answer this, but maybe it will come handy for someone else.
Simplest way:
var someString = "...";
var someRegex = "...";
var match = Regex.Match(someString , someRegex );
if(match.Success && match.Value.Length == someString.Length){
//pass
} else {
//fail
}
Use the ^ and $ modifiers to denote where the regex pattern sits relative to the start and end of the string:
Regex.Match("Red October", "^Red October$"); // pass
Regex.Match("The Hunt for Red October", "^Red October$"); // fail
You need to enclose your regex in ^ (start of string) and $ (end of string):
^Red October$
If the string may contain regex metasymbols (. { } ( ) $ etc), I propose to use
^\QYourString\E$
\Q starts quoting all the characters until \E.
Otherwise the regex can be unappropriate or even invalid.
If the language uses regex as string parameter (as I see in the example), double slash should be used:
^\\QYourString\\E$
Hope this tip helps somebody.
Sorry, but that's a little unclear.
From what i read, you want to do simple string compare. You don't need regex for that.
string myTest = "Red October";
bool isMatch = (myTest.ToLower() == "Red October".ToLower());
Console.WriteLine(isMatch);
isMatch = (myTest.ToLower() == "The Hunt for Red October".ToLower());
You can do it like this Exemple if i only want to catch one time the letter minus a in a string and it can be check with myRegex.IsMatch()
^[^e][e]{1}[^e]$
I need a regex that will only find matches where the entire string matches my query.
For instance if I do a search for movies with the name "Red October" I only want to match on that exact title (case insensitive) but not match titles like "The Hunt For Red October". Not quite sure I know how to do this. Anyone know?
Thanks!
Try the following regular expression:
^Red October$
By default, regular expressions are case sensitive. The ^ marks the start of the matching text and $ the end.
Generally, and with default settings, ^ and $ anchors are a good way of ensuring that a regex matches an entire string.
A few caveats, though:
If you have alternation in your regex, be sure to enclose your regex in a non-capturing group before surrounding it with ^ and $:
^foo|bar$
is of course different from
^(?:foo|bar)$
Also, ^ and $ can take on a different meaning (start/end of line instead of start/end of string) if certain options are set. In text editors that support regular expressions, this is usually the default behaviour. In some languages, especially Ruby, this behaviour cannot even be switched off.
Therefore there is another set of anchors that are guaranteed to only match at the start/end of the entire string:
\A matches at the start of the string.
\Z matches at the end of the string or before a final line break.
\z matches at the very end of the string.
But not all languages support these anchors, most notably JavaScript.
I know that this may be a little late to answer this, but maybe it will come handy for someone else.
Simplest way:
var someString = "...";
var someRegex = "...";
var match = Regex.Match(someString , someRegex );
if(match.Success && match.Value.Length == someString.Length){
//pass
} else {
//fail
}
Use the ^ and $ modifiers to denote where the regex pattern sits relative to the start and end of the string:
Regex.Match("Red October", "^Red October$"); // pass
Regex.Match("The Hunt for Red October", "^Red October$"); // fail
You need to enclose your regex in ^ (start of string) and $ (end of string):
^Red October$
If the string may contain regex metasymbols (. { } ( ) $ etc), I propose to use
^\QYourString\E$
\Q starts quoting all the characters until \E.
Otherwise the regex can be unappropriate or even invalid.
If the language uses regex as string parameter (as I see in the example), double slash should be used:
^\\QYourString\\E$
Hope this tip helps somebody.
Sorry, but that's a little unclear.
From what i read, you want to do simple string compare. You don't need regex for that.
string myTest = "Red October";
bool isMatch = (myTest.ToLower() == "Red October".ToLower());
Console.WriteLine(isMatch);
isMatch = (myTest.ToLower() == "The Hunt for Red October".ToLower());
You can do it like this Exemple if i only want to catch one time the letter minus a in a string and it can be check with myRegex.IsMatch()
^[^e][e]{1}[^e]$
I need a regex that will only find matches where the entire string matches my query.
For instance if I do a search for movies with the name "Red October" I only want to match on that exact title (case insensitive) but not match titles like "The Hunt For Red October". Not quite sure I know how to do this. Anyone know?
Thanks!
Try the following regular expression:
^Red October$
By default, regular expressions are case sensitive. The ^ marks the start of the matching text and $ the end.
Generally, and with default settings, ^ and $ anchors are a good way of ensuring that a regex matches an entire string.
A few caveats, though:
If you have alternation in your regex, be sure to enclose your regex in a non-capturing group before surrounding it with ^ and $:
^foo|bar$
is of course different from
^(?:foo|bar)$
Also, ^ and $ can take on a different meaning (start/end of line instead of start/end of string) if certain options are set. In text editors that support regular expressions, this is usually the default behaviour. In some languages, especially Ruby, this behaviour cannot even be switched off.
Therefore there is another set of anchors that are guaranteed to only match at the start/end of the entire string:
\A matches at the start of the string.
\Z matches at the end of the string or before a final line break.
\z matches at the very end of the string.
But not all languages support these anchors, most notably JavaScript.
I know that this may be a little late to answer this, but maybe it will come handy for someone else.
Simplest way:
var someString = "...";
var someRegex = "...";
var match = Regex.Match(someString , someRegex );
if(match.Success && match.Value.Length == someString.Length){
//pass
} else {
//fail
}
Use the ^ and $ modifiers to denote where the regex pattern sits relative to the start and end of the string:
Regex.Match("Red October", "^Red October$"); // pass
Regex.Match("The Hunt for Red October", "^Red October$"); // fail
You need to enclose your regex in ^ (start of string) and $ (end of string):
^Red October$
If the string may contain regex metasymbols (. { } ( ) $ etc), I propose to use
^\QYourString\E$
\Q starts quoting all the characters until \E.
Otherwise the regex can be unappropriate or even invalid.
If the language uses regex as string parameter (as I see in the example), double slash should be used:
^\\QYourString\\E$
Hope this tip helps somebody.
Sorry, but that's a little unclear.
From what i read, you want to do simple string compare. You don't need regex for that.
string myTest = "Red October";
bool isMatch = (myTest.ToLower() == "Red October".ToLower());
Console.WriteLine(isMatch);
isMatch = (myTest.ToLower() == "The Hunt for Red October".ToLower());
You can do it like this Exemple if i only want to catch one time the letter minus a in a string and it can be check with myRegex.IsMatch()
^[^e][e]{1}[^e]$
I'm new in regular expressions. I've got a little problem and i can't find the answer. I'm looking for redundant brackets using this regular espression:
public Regex RedundantBrackets = new Regex("[(](\\s?)[a-z](\\s?)[)]");
When i find something i want to modife string in this way:
text1 (text2) text3 => text1 text2 text3 - so as you can se i want only to remove brackets. How can i do this? I was trying to use Replace method, but using it i can only replace every sign of "(text2)".
Thanks in advance!
Try this replace
Regex.Replace("text1 (text2) text3", // Input
#"([()])", // Pattern to match
string.Empty) // Item to replace
/* result: text1 text2 text3*/
Explanation
Regex replace looks across the whole string for a match. If it finds a match it will replace that item. So our match pattern looks like this ([()]). Which means this
( is what is required within the pattern to start the match and needs a closing ) otherwise the match pattern is not balanced.
[] in the pattern says, I am searching for a character, and [ and ] define a set. They are considered set matches. The most common one is [A-Z] which is any set of characters, starting with A and ending in Z. We will define our own set. *Remember [ and ] mean to regex we are looking for 1 character but we specify a set of many characters within that.
( and ) within our set [()] which also could be specified as [)(] as well means we have a set of two characters. Those two characters are the opening and closing parenthesis ().
So taken all together we are looking to match (1) any character in the set (2) that is either a ( or a ). When that match is found, replace the ( or ) with string.empty.
When we run the regex replace on your text it finds two matches the (text2 and finally the match text2). Those are replaced with string.empty.
First off, it can be handy to use verbatim strings so you don't have to escape the slashes etc.
public Regex RedundantBrackets = new Regex(#"[(]\s?([a-z]+)\s?[)]");
We want to wrap [a-z] in parenthesis because that's what we're trying to capture. We can then use $1 to place that capture into the replacement
RedundantBrackets.Replace("text (text) text", "$1");
EDIT: I forgot to add repetition to [a-z] => [a-z]+
this will remove all charaters using regex
finalString = Regex.Replace(finalString, #"[^\w ]", "");
I need a help with regular expression as I do not have good knowledge in it.
I have regular expression as:
Regex myregex = new Regex("testValue=\"(.+?)\"");
What does (.+?) indicate?
The string it matches is "testValue=123e4567" and returns 123e4567 as output.
Now I need help in regular expression to match a string "<helpMe>123e4567</helpMe>" where I need 123e4567 as output. How do I write a regular expression for it?
This means:
( Begin captured group
. Match any character
+ One or more times
? Non-greedy quantifier
) End captured group
In the case of your regex, the non-greedy quantifier ? means that your captured group will begin after the first double-quote, and then end immediately before the very next double-quote it encounters. If it were greedy (without the ?), the group would extend to the very last double-quote it encounters on that line (i.e., "greedily" consuming as much of the line as possible).
For your "helpMe" example, you'd want this regex:
<helpMe>(.+?)</helpMe>
Given this string:
<div>Something<helpMe>ABCDE</helpMe></div>
You'd get this match:
ABCDE
The value of the non-greedy quantifier is evident in this variation:
Regex: <helpMe>(.+)</helpMe>
String: <div>Something<helpMe>ABCDE</helpMe><helpMe>FGHIJ</helpMe></div>
The greedy capture would look like this:
ABCDE</helpMe><helpMe>FGHIJ
There are some useful interactive tools to play with these variations:
Regex Tester
Regex Pal
Ken Redler has a great answer regarding your first question. For the second question try:
<(helpMe)>(.*?)</\1>
Using the back reference \1 you can find values between the set of matching tags. The first group finds the tag name, the second group matches the content itself, and the \1 back reference re-uses the first group's match (in this case the tag name).
Also, in C# you can use named groups, like: <(helpMe)>(?<value>.*?)</\1> where now match.Groups["value"].Value contains your value.
What does (.+?) indicate?
It means match any character (.) one or more times (+?)
A simple regex to match your second string would be
<helpMe>([a-z0-9]+)<\/helpMe>
This will match any character of a-z and any digit inside <helpme> and </helpMe>.
The pharanteses are used to capture a group. This is useful if you need to reference the value inside this group later.