I have a string to parse. First I have to check if string contains special pattern:
I wanted to know if there is substrings which starts with "$(",
and end with ")",
and between those start and end special strings,there should not be
any white-empty space,
it should not include "$" character inside it.
I have a little regex for it in C#
string input = "$(abc)";
string pattern = #"\$\(([^$][^\s]*)\)";
Regex rgx = new Regex(pattern, RegexOptions.IgnoreCase);
MatchCollection matches = rgx.Matches(input);
foreach (var match in matches)
{
Console.WriteLine("value = " + match);
}
It works for many cases but failed at input= $(a$() , which inside the expression is empty. I wanted NOT to match when input is $().[ there is nothing between start and end identifiers].
What is wrong with my regex?
Note: [^$] matches a single character but not of $
Use the below regex if you want to match $()
\$\(([^\s$]*)\)
Use the below regex if you don't want to match $(),
\$\(([^\s$]+)\)
* repeats the preceding token zero or more times.
+ Repeats the preceding token one or more times.
Your regex \(([^$][^\s]*)\) is wrong. It won't allow $ as a first character inside () but it allows it as second or third ,, etc. See the demo here. You need to combine the negated classes in your regex inorder to match any character not of a space or $.
Your current regex does not match $() because the [^$] matches at least 1 character. The only way I can think of where you would have this match would be when you have an input containing more than one parens, like:
$()(something)
In those cases, you will also need to exclude at least the closing paren:
string pattern = #"\$\(([^$\s)]+)\)";
The above matches for example:
abc in $(abc) and
abc and def in $(def)$()$(abc)(something).
Simply replace the * with a + and merge the options.
string pattern = #"\$\(([^$\s]+)\)";
+ means 1 or more
* means 0 or more
Related
I have a regex that takes out all parts of a string in between citation marks.
\(([^)]*)\)
So
*- (Hello) + (World) -
returns two matches
(Hello)
(World)
Im trying but failing to modify it so that i also get the parts in between as their own matches. Like:
*-
(Hello)
+
(World)
-
Is it even possible?
In this case, with the current regex, you may use Regex.Split with the pattern wrapped in a capturing group:
var tokens = Regex.Split(s, #"(\([^)]*\))");
Or even, when matches occur in the leading/trailing positions:
var tokens = Regex.Split(s, #"(\([^)]*\))").Where(m => !string.IsNullOrEmpty(m));
See the regex demo:
Note you may need to replace all capturing groups in your regex into non-capturing to use this feature. When you use "technical" capturing groups to later refer to using backreferences, you would have to build the non-matching substring array using multiple matching and calling .Substring() on the input using the information on the match position.
You could use an alternation to match either the parenthesis with the characters \([^)]*\) or | match one or more times the characters listed in a character class [*+-]+
\([^)]*\)|[*+-]+
string pattern = #"\([^)]*\)|[*+-]+";
string input = #"*- (Hello) + (World) - ";
foreach (Match m in Regex.Matches(input, pattern))
{
Console.WriteLine(m.Value);
}
That would give you:
*-
(Hello)
+
(World)
-
Demo C#
I'm looking for a way to search a string for everything before a set of characters in C#. For Example, if this is my string value:
This is is a test.... 12345
I want build a new string with all of the characters before "12345".
So my new string would equal "This is is a test.... "
Is there a way to do this?
I've found Regex examples where you can focus on one character but not a sequence of characters.
You don't need to use a Regex:
public string GetBitBefore(string text, string end)
{
var index = text.IndexOf(end);
if (index == -1) return text;
return text.Substring(0, index);
}
You can use a lazy quantifier to match anything, followed by a lookahead:
var match = Regex.Match("This is is a test.... 12345", #".*?(?=\d{5})");
where:
.*? lazily matches everything (up to the lookahead)
(?=…) is a positive lookahead: the pattern must be matched, but is not included in the result
\d{5} matches exactly five digits. I'm assuming this is your lookahead; you can replace it
You can do so with help of regex lookahead.
.*(?=12345)
Example:
var data = "This is is a test.... 12345";
var rxStr = ".*(?=12345)";
var rx = new System.Text.RegularExpressions.Regex (rxStr,
System.Text.RegularExpressions.RegexOptions.IgnoreCase);
var match = rx.Match(data);
if (match.Success) {
Console.WriteLine (match.Value);
}
Above code snippet will print every thing upto 12345:
This is is a test....
For more detail about see regex positive lookahead
This should get you started:
var reg = new Regex("^(.+)12345$");
var match = reg.Match("This is is a test.... 12345");
var group = match.Groups[1]; // This is is a test....
Of course you'd want to do some additional validation, but this is the basic idea.
^ means start of string
$ means end of string
The asterisk tells the engine to attempt to match the preceding token zero or more times. The plus tells the engine to attempt to match the preceding token once or more
{min,max} indicate the minimum/maximum number of matches.
\d matches a single character that is a digit, \w matches a "word character" (alphanumeric characters plus underscore), and \s matches a whitespace character (includes tabs and line breaks).
[^a] means not so exclude a
The dot matches a single character, except line break characters
In your case there many way to accomplish the task.
Eg excluding digit: ^[^\d]*
If you know the set of characters and they are not only digit, don't use regex but IndexOf(). If you know the separator between first and second part as "..." you can use Split()
Take a look at this snippet:
class Program
{
static void Main(string[] args)
{
string input = "This is is a test.... 12345";
// Here we call Regex.Match.
MatchCollection matches = Regex.Matches(input, #"(?<MySentence>(\w+\s*)*)(?<MyNumberPart>\d*)");
foreach (Match item in matches)
{
Console.WriteLine(item.Groups["MySentence"]);
Console.WriteLine("******");
Console.WriteLine(item.Groups["MyNumberPart"]);
}
Console.ReadKey();
}
}
You could just split, not as optimal as the indexOf solution
string value = "oiasjdoiasj12345";
string end = "12345";
string result = value.Split(new string[] { end }, StringSplitOptions.None)[0] //Take first part of the result, not the quickest but fairly simple
I want to create a regular expression to match a word that begins with a period. The word(s) can exist N times in a string. I want to ensure that the word comes up whether it's at the beginning of a line, the end of a line or somewhere in the middle. The latter part is what I'm having difficulty with.
Here is where I am at so far.
const string pattern = #"(^|(.* ))(?<slickText>\.[a-zA-Z0-9]*)( .*|$)";
public static MatchCollection Find(string input)
{
Regex regex = new Regex(pattern,RegexOptions.IgnoreCase | RegexOptions.Multiline);
MatchCollection collection = regex.Matches(input);
return collection;
}
My test pattern finds .lee and .good. My test pattern fails to find .bruce:
static void Main()
{
MatchCollection results = ClassName.Find("a short stump .bruce\r\nand .lee a small tree\r\n.good roots");
foreach (Match item in results)
{
GroupCollection groups = item.Groups;
Console.WriteLine("{0} ", groups["slickText"].Value);
}
System.Diagnostics.Debug.Assert(results.Count > 0);
}
Maybe you're just looking for \.\w+?
Test:
var s = "a short stump .bruce\r\nand .lee a small tree\r\n.good roots";
Regex.Matches(s, #"\.\w+").Dump();
Result:
Note:
If you don't want to find foo in some.foo (because there's no whitespace between some and .foo), you can use (?<=\W|^)\.\w+ instead.
Bizarrely enough, it seems that with RegexOptions.Multiline, ^ and $ will only additionally match \n, not \r\n.
Thus you get .good because it is preceded by \n which is matched by ^, but you don't get .bruce because it is succeeded by \r which is not matched by $.
You could do a .Replace("\r", "") on the input, or rewrite your expression to take individual lines of input.
Edit: Or replace $ with \r?$ in your pattern to explicitly include the \r; thanks to SvenS for the suggestion.
In your RegEx, a word has to be terminated by a space, but bruce is terminated by \r instead.
I would give this regex a go:
(?:.*?(\.[A-Za-z]+(?:\b|.\s)).*?)+
And change the RegexOptions from Multiline to Singleline - in this mode dot matches all characters including newline.
I'm trying to create a regex expression what will accept a certain format of command. The pattern is as follows:
Can start with a $ and have two following value 0-9,A-F,a-f (ie: $00 - $FF)
or
Can be any value except for "&<>'/"
*if the value start with $ the next two values after need to be a valid hex value from 00-ff
So far I have this
Regex correctValue = new Regex("($[0-9a-fA-F][0-9a-fA-F])");
Any help will be greatly appreciated!
You just need to add "\" symbol before your "$" and it works:
string input = "$00";
Match m = Regex.Match(input, #"^\$[0-9a-fA-F][0-9a-fA-F]$");
if (m.Success)
{
foreach (Group g in m.Groups)
Console.WriteLine(g.Value);
}
else
Console.WriteLine("Didn't match");
If I'm following you correctly, the net result you're looking for is any value that is not in the list "&<>'/", since any combination of $ and two alphanumeric characters would also not be in that list. Thus you could make your expression:
Regex correctValue = new Regex("[^&<>'/]");
Update: But just in case you do need to know how to properly match the $00 - $FF, this would do the trick:
Regex correctValue = new Regex("\$[0-9A-Fa-f]{2}");
In Regular Expression $ use for Anchor assertion, and means:
The match must occur at the end of the string or before \n at the end of the line or string.
try using [$] (Character Class for single character) or \$ (Character Escape) instead.
I need to match the following strings and returns the values as groups:
abctic
abctac
xyztic
xyztac
ghhtic
ghhtac
Pattern is wrote with grouping is as follows:
(?<arch>[abc,xyz,ghh])(?<flavor>[tic,tac]$)
The above returns only parts of group names. (meaning match is not correct).
If I use * in each sub pattern instead of $ at the end, groups are correct, but that would mean that abcticff will also match.
Please let me know what my correct regex should be.
Your pattern is incorrect because a pipe symbol | is used to specify alternate matches, not a comma in brackets as you were using, i.e., [x,y].
Your pattern should be: ^(?<arch>abc|xyz|ghh)(?<flavor>tic|tac)$
The ^ and $ metacharacters ensures the string matches from start to end. If you need to match text in a larger string you could replace them with \b to match on a word boundary.
Try this approach:
string[] inputs = { "abctic", "abctac", "xyztic", "xyztac", "ghhtic", "ghhtac" };
string pattern = #"^(?<arch>abc|xyz|ghh)(?<flavor>tic|tac)$";
foreach (var input in inputs)
{
var match = Regex.Match(input, pattern);
if (match.Success)
{
Console.WriteLine("Arch: {0} - Flavor: {1}",
match.Groups["arch"].Value,
match.Groups["flavor"].Value);
}
else
Console.WriteLine("No match for: " + input);
}