I need some advice. Suppose I have the following string: Read Variable
I want to find all pieces of text like this in a string and make all of them like the following:Variable = MessageBox.Show. So as aditional examples:
"Read Dog" --> "Dog = MessageBox.Show"
"Read Cat" --> "Cat = MessageBox.Show"
Can you help me? I need a fast advice using RegEx in C#. I think it is a job involving wildcards, but I do not know how to use them very well... Also, I need this for a school project tomorrow... Thanks!
Edit: This is what I have done so far and it does not work: Regex.Replace(String, "Read ", " = Messagebox.Show").
You can do this
string ns= Regex.Replace(yourString,"Read\s+(.*?)(?:\s|$)","$1 = MessageBox.Show");
\s+ matches 1 to many space characters
(.*?)(?:\s|$) matches 0 to many characters till the first space (i.e \s) or till the end of the string is reached(i.e $)
$1 represents the first captured group i.e (.*?)
You might want to clarify your question... but here goes:
If you want to match the next word after "Read " in regex, use Read (\w*) where \w is the word character class and * is the greedy match operator.
If you want to match everything after "Read " in regex, use Read (.*)$ where . will match all characters and $ means end of line.
With either regex, you can use a replace of $1 = MessageBox.Show as $1 will reference the first matched group (which was denoted by the parenthesis).
Complete code:
replacedString = Regex.Replace(inStr, #"Read (.*)$", "$1 = MessageBox.Show");
The problem with your attempt is, that it cannot know that the replacement string should be inserted after your variable. Let's assume that valid variable names contain letters, digits and underscores (which can be conveniently matched with \w). That means, any other character ends the variable name. Then you could match the variable name, capture it (using parentheses) and put it in the replacement string with $1:
output = Regex.Replace(input, #"Read\s+(\w+)", "$1 = MessageBox.Show");
Note that \s+ matches one or more arbitrary whitespace characters. \w+ matches one or more letters, digits and underscores. If you want to restrict variable names to letters only, this is the place to change it:
output = Regex.Replace(input, #"Read\s+([a-zA-Z]+)", "$1 = MessageBox.Show");
Here is a good tutorial.
Finally note, that in C# it is advisable to write regular expressions as verbatim strings (#"..."). Otherwise, you will have to double escape everything, so that the backslashes get through to the regex engine, and that really lessens the readability of the regex.
Related
I want to spilt Alphanumeric with two part Alpha and numeric with special character like -
string mystring = "1- Any Thing"
I want to store like:
numberPart = 1
alphaPart = Any Thing
For this i am using Regex
Regex re = new Regex(#"([a-zA-Z]+)(\d+)");
Match result = re.Match("1- Any Thing");
string alphaPart = result.Groups[1].Value;
string numberPart = result.Groups[2].Value;
If there is no space in between string its working fine but space and symbol both alphaPart and numberPart showing null where i am doing wrong Might be Regex expression is wrong for this type of filter please suggest me on same
Try this:
(\d+)(?:[^\w]+)?([a-zA-Z\s]+)
Demo
Explanation:
(\d+) - capture one or more digit
[^\w]+ match anything except alphabets
? this tell that anything between word and number can appear or not(when not space is between them)
[a-zA-Z\s]+ match alphabets(even if between them have spaces)
Start of string is matched with ^.
Digits are matched with \d+.
Any non-alphanumeric characters are matched with [\W_] or \W.
Anything is matched with .*.
Use
(?s)^(\d+)\W*(.*)
See proof
(?s) makes . match linebreaks. So, it literally matches everything.
So i have the following RegEx for the purpose of finding and adding whitespace:
(\S)(\()
So for a string like "SomeText(Somemoretext)" I want to update this to "SomeText (Somemoretext)" it matches "t(" and so my replace eliminates the "t" from the string which is not good. I also do not know what the character could be, I'm merely trying to find the non-existence of whitespace.
Is there a better expression to use or is there a way to exclude the found character from the match returned so that I can safely replace without catching characters i do not want to replace?
Thanks
I find lookarounds hard to read and would prefer using substitutions in the replacement string instead:
var s = Regex.Replace("test1() test2()", #"(\S)\(", "$1 (");
Debug.Assert(s == "test1 () test2 ()");
$1 inserts the first capture group from the regex into the replacement string which is the non-space character before the opening parenthesis (.
If you need to detect the absence of space before a specific character (such as bracket) after a word, how about the following?
\b(?=[^\s])\(
This will detect words ( [a-zA-z0-9_] that are followed by a bracket, without a space).
(if I got your problem correctly) you can replace the full match with ( and get exactly what you need.
In case you need to look for absence spaces before a symbol (like a bracket) in any kind of text (as in the text may be non-word, such as punctuation) you might want to use the following instead.
^(?:\S*)(\()(?:\S*)$
When using this, your result will be in group 1, instead of just full match (which now contains the whole line, if a line is matched).
I have string that I would like to remove any word following a "\", whether in the middle or at the end, such as:
testing a\determiner checking test one\pronoun
desired result:
testing a checking test one
I have tried a simple regex that removes anything between the backslash and whitespace, but it gives the following result:
string input = "testing a\determiner checking test one\pronoun";
Regex regex = new Regex(#"\\.*\s");
string output = regex.Replace(input, " ");
Result:
testing a one\pronoun
It looks like this regex matches from the backslash until the last whitespace in the string. I cannot seem to figure out how to match from the backlash to the next whitespace. Also, I am not guaranteed a whitespace at the end, so I would need to handle that. I could continue processing the string and remove any text after the backslash, but I was hoping I could handle both cases with one step.
Any advice would be appreciated.
Change .* which match any characters, to \w*, which only match word characters.
Regex regex = new Regex(#"\\\w*");
string output = regex.Replace(input, "");
".*" matches zero or more characters of any kind. Consider using "\w+" instead, which matches one or more "word" characters (not including whitespace).
Using "+" instead of "*" would allow a backslash followed by a non-"word" character to remain unmatched. For example, no matches would be found in the sentence "Sometimes I experience \ an uncontrollable compulsion \ to intersperse backslash \ characters throughout my sentences!"
With your current pattern, .* tells the parser to be "greedy," that is, to take as much of the string as possible until it hits a space. Adding a ? right after that * tells it instead to make the capture as small as possible--to stop as soon as it hits the first space.
Next, you want to end at not just a space, but at either a space or the end of the string. The $ symbol captures the end of the string, and | means or. Group those together using parentheses and your group collectively tells the parser to stop at either a space or the end of the string. Your code will look like this:
string input = #"testing a\determiner checking test one\pronoun";
Regex regex = new Regex(#"\\.*?(\s|$)");
string output = regex.Replace(input, " ");
Try this regex (\\[^\s]*)
(\\[^\s]*)
1st Capturing group (\\[^\s]*)
\\ matches the character \ literally
[^\s]* match a single character not present in the list below
Quantifier: * Between zero and unlimited times, as many times as possible, giving back as needed [greedy]
\s match any white space character [\r\n\t\f ].
I'm quite the Regex novice, but I have a series of strings similar to this "[$myVar.myVar_STATE]" I need to replace the 2nd myVar that begins with a period and ends with an underscore. I need it to match it exactly, as sometimes I'll have "[$myVar.myVar_moreMyVar_STATE]" and in that case I wouldn't want to replace anything.
I've tried things like "\b.myVar_\b", "\.\bmyVar_\b" and several more, all to no luck.
How about this:
\[\$myVar\.([^_]+)_STATE\]
Matches:
[$myVar.myVar_STATE] // matches and captures 'myvar'
[$myVar.myVar_moreMyVar_STATE] // no match
Working regex example:
http://regex101.com/r/yM9jQ3
Or if _STATE was variable, you could use this: (as long as the text in the STATE part does not have underscores in it.)
\[\$myVar\.([^_]+)_[^_]+\]
Working regex example:
http://regex101.com/r/kW8oE1
Edit: Conforming to OP's comments below, This should be what he's going for:
(\[\$myVar\.)([^_]+)(_[^_]+\])
Regex replace example:
http://regex101.com/r/pU6yL8
C#
var pattern = #"(\[\$myVar\.)([^_]+)(_[^_]+\])";
var replaced = Regex.Replace(input, pattern, "$1"+ newVar + "$3")
What about something like:
.*.(myVar_).*
This looks for anything then a . and "myVar_" followed by anything.
It matches:
"[$myVar.myVar_STATE]"
And only the first myVar_ here:
"[$myVar.myVar_moremyVar_STATE]"
See it in action.
This should do it:
\[\$myVar\.(.*?)_STATE\]
You can use this little trick to pick out the groups, and build the replacement at the end, like so:
var replacement = "something";
var input = #"[$myVar.myVar_STATE]";
var pattern = #"(\[\$myVar\.)(.*?)_(.*?)]";
var replaced = Regex.Replace(input, pattern, "$1"+ replacement + "_$2]")
C# already has builtin method to do this
string text = ".asda_";
Response.Write((text.StartsWith(".") && text.EndsWith("_")));
Is Regex really required?
string input = "[$myVar.myVar_STATE]";
string oldVar = "myVar";
string newVar = "myNewVar";
string result = input.Replace("." + oldVar + "_STATE]", "." + newVar + "_STATE]");
In case "STATE" is a variable part, then we'll need to use Regex. The easiest way is to use this Regex pattern which matches a position between a prefix and a suffix. Prefix and suffix are used for searching but are not included in the resulting match:
(?<=prefix)find(?=suffix)
result =
Regex.Replace(input, #"(?<=\.)" + Regex.Escape(oldVar) + "(?=_[A-Z]+])", newVar);
Explanation:
The prefix part is \., which stand for ".".
The find part is the escaped old variable to be replaced. Regex escaping makes sure that characters with a special meaning in Regex are escaped.
The suffix part is _[A-Z]+], an underscore followed by at least one letter followed by "]". Note: the second ] needs not to be escaped. An opening bracket [ would have to be escaped like this: \[. We cannot use \w for word characters for the STATE-part as \w includes underscores. You might have to adapt the [A-Z] part to exactly match all possible states (e.g. if state has digits, use [A-Z0-9].
I'm after a regex for C# which will turn this:
"*one*" *two** two and a bit "three four"
into this:
"*one*" "*two**" two and a bit "three four"
IE a quoted string should be unchanged whether it contains one or many words.
Any words with asterisks to be wrapped in double quotes.
Any unquoted words with no asterisks to be unchanged.
Nice to haves:
If multiple asterisks could be merged into one in the same step that would be better.
Noise words - eg and, a, the - which are not part of a quoted string should be dumped.
Thanks for any help / advice.
Julio
The following regex will do what you're looking for:
\*+ # Match 1 or more *
(
\w+ # Capture character string
)
\*+ # Match 1 or more *
If you use this in conjunction with this replace statement, all you words matched by (\w+) will be wrapped in "**":
string s = "\"one\" *two** two and a bit \"three four\"";
Regex r = new Regex(#"\*+(\w+)\*+");
var output = r.Replace(s, #"""*$1*""");
Note: This will leave the below string unquoted:
*two two*
If you wish to match those strings as well, use this regex:
\*+([^*]+)\*+
EDIT: updated code.
This solution works for your request, as well as the nice to have items:
string text = #"test the ""one"" and a *two** two and a the bit ""three four"" a";
string result = Regex.Replace(text, #"\*+(.*?)\*+", #"""*$1*""");
string noiseWordsPattern = #"(?<!"") # match if double quote prefix is absent
\b # word boundary to prevent partial word matches
(and|a|the) # noise words
\b # word boundary
(?!"") # match if double quote suffix is absent
";
// to use the commented pattern use RegexOptions.IgnorePatternWhitespace
result = Regex.Replace(result, noiseWordsPattern, "", RegexOptions.IgnorePatternWhitespace);
// or use this one line version instead
// result = Regex.Replace(result, #"(?<!"")\b(and|a|the)\b(?!"")", "");
// remove extra spaces resulting from noise words replacement
result = Regex.Replace(result, #"\s+", " ");
Console.WriteLine("Original: {0}", text);
Console.WriteLine("Result: {0}", result);
Output:
Original: test the "one" and a *two** two and a the bit "three four" a
Result: test "one" "*two*" two bit "three four"
The 2nd regex replacement for noise words causes potential duplicate of blank spaces. To remedy this side effect I added the 3rd regex replacement to clean it up.
Something like this. ArgumentReplacer is a callback that is called for each match. The return value is substituted into the returned string.
void Main() {
string text = "\"one\" *two** and a bit \"three *** four\"";
string finderRegex = #"
(""[^""]*"") # quoted
| ([^\s""*]*\*[^\s""]*) # with asteriks
| ([^\s""]+) # without asteriks
";
return Regex.Replace(text, finderRegex, ArgumentReplacer,
RegexOptions.IgnorePatternWhitespace);
}
public static String ArgumentReplacer(Match theMatch) {
// Don't touch quoted arguments, and arguments with no asteriks
if (theMatch.Groups[2].Value.Length == 0)
return theMatch.Value;
// Quote arguments with asteriks, and replace sequences of such
// by a single one.
return String.Format("\"%s\"",
Regex.Replace(theMatch.Value, #"\*\*+", "*"));
}
Alternatives to the left in the pattern has priority over those to the right. This is why I just needed to write "[^\s""]+" in the last alternative.
The quotes, on the other hand, are only matched if they occur at the beginning of the argument. They will not be detected if they occur in the middle of the argument, and we must stop before those if they occur.
Given that you wish to match pairs of quotes, I don’t think your language is regular, therefore I don’t think RegEx is a good solution. E.g
Some people, when confronted with a problem, think “I know, I'll use
regular expressions.”
Now they have two problems.
See "When not to use Regex in C# (or Java, C++ etc)"
I've decided to follow the advice of a couple of responses and go with a parser solution. I've tried the regexes contributed so far and they seem to fail in some cases. That's probably an indication that regexes aren't the appropriate solution to this problem. Thanks for all responses.