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]$
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 have created a Regex as below, but the Match method does not work correctly:
Regex regex = new Regex("(" + SearchText + ")", RegexOptions.IgnoreCase);
if(regex.Match(item).Success) { ... }
For example, if I set SearchText to e., and i set item to es, then Success is true.
Similarly, if have set SearchText to $ or ., then a match with 4 returns Success as true.
How come this is happening, and how can I solve this problem?
When you use a regex there are a bunch of common characters which have special meanings. For example, the period (.) character will match any character at all so if you wanted to match the words dog and dig, you could use the regex d.g.
There are MANY different special characters you can use, you should see the full .NET Regex documentation for more details.
This makes matching specific things slightly more complicated when you want to match something specific, like the end of a sentence. To match dog. you actually have to pass in dog\. as the regex to match against. You can use the Regex.Escape(string str) method to escape most simple strings, before passing them into your Regex constructor.
The other question is if you are only looking for literals, why do you use Regex at all.
string item = "bla bla e. bla";
bool result = item.Contains("e."); //returns true
Edit
Case insensitive:
result = item.IndexOf("e.", 0, StringComparison.OrdinalIgnoreCase) != -1;
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
In C#, how would I capture the integer value in the URL like:
/someBlah/a/3434/b/232/999.aspx
I need to get the 999 value from the above url.
The url HAS to have the /someBlah/ in it.
All other values like a/3434/b/232/ can be any character/number.
Do I have escape for the '/' ?
Try the following
var match = Regex.Match(url,"^http://.*someblah.*\/(\w+).aspx$");
if ( match.Success ) {
string name = match.Groups[1].Value;
}
You didn't specify what names could appear in front of the ASPX file. I took the simple approach of using the \w regex character which matches letters and digits. You can modify it as necessary to include other items.
You are effectively getting the file name without an extension.
Although you specifically asked for a regular expression, unless you are in a scenario where you really need to use one, I'd recommend that you use System.IO.Path.GetFileNameWithoutExtension:
Path.GetFileNameWithoutExtension(Context.Request.FilePath)
^(?:.+/)*(?:.+)?/someBlah/(?:.+/)*(.+)\.aspx$
This is a bit exhaustive, but it can handle scenarios where /someBlah/ does not have to be at the beginning of the string.
The ?: operator implies a non-capturing group, which may or may not be supported by your RegEx flavor.
Regex regex = new Regex("^http://.*someBlah.*/(\\d+).aspx$");
Match match = regex.Match(url);
int result;
if (match.Success)
{
int.TryParse(match.Groups[1].Value, out result);
}
Using \d rather than \w ensures that you only match digits, and unless the ignore case flag is set the capitalisation of someBlah must be correct.