I need to replace a series of characters in a file name in C#. After doing many searches, I can't find a good example of replacing all characters between two specific ones. For example, the file name would be:
"TestExample_serialNumber_Version_1.0_.pdf"
All I want is the final product to be "serialNumber".
Is there a special character I can use to replace all characters up to and including the first underscore? Then I can run the the replace method again to replace everything after the and including the next underscore? I've heard of using regex but I've done something similar to this in Java and it seemed much easier to accomplish. I must not be understanding the string formats in C#.
I would imagine it would look something like:
name.Replace("T?_", "");//where ? equals any characters between
name.Replace("_?", "");
Rather than "replace", just use a regex to extract the part you want. Something like:
(?:TestExample_)(.*)(?:_Version)
Would give you the serialnumber part in a capture group.
Or if TestExample is variable (in which case, you need your question to be more specific about exactly what patten you are matching) you could probably just do:
(?:_)(.*)(?:_Version)
Assuming the Version part is constant.
In C#, you could do something like:
var regex1 = new Regex("(?:TestExample_)(.*)(?:_Version)");
string testString = "TestExample_serialNumber_Version_1.0_.pdf";
string serialNum = regex1.Match(testString).Groups[1].Value;
As an alternative to regex, you could find the first instance of an underscore then find the next instance of an underscore and take the substring between those indices.
string myStr = "TestExample_serialNumber_Version_1.0_.pdf";
string splitStr = "_";
int startIndex = myStr.IndexOf(splitStr) + 1;
string serialNum = myStr.Substring(startIndex, myStr.IndexOf(splitStr, startIndex) - startIndex);
Related
How can I use regex to replace matching strings that do not include a specific string?
input string
Keepword mywordsecond mythirdword myfourthwordKeep
string to replace
word
exclude string
Keep
Desired out put
Keepword mysecond mythird myfourthKeep
Will there ever be more than one word in a word? If there are more than one, do you want to replace all of them? If not, this should sort you out:
Regex r = new Regex(#"\b((?:(?!Keep|word)\w)*)word((?:(?!Keep)\w)*)\b");
s1 = r.Replace(s0, "$1$2");
to explain:
First, \b((?:(?!Keep|word)\w)*) captures whatever text precedes the first occurrence of word or Keep.
The next thing it sees must be word, If it sees Keep or the end of the string instead, the match attempt immediately fails.
Then ((?:(?!Keep)\w)*)\b captures the remainder of the text in order to ensure it doesn't contain Keep.
When faced with a problem like this, most users' first impulse is to match (in the sense of consuming) only the part of the string they're interested in, using lookarounds to establish the context. It's usually much easier to write the regex so that it always moves forward through the string as it matches. You capture the parts you want to retain so you can plug them back into the result string by means of group references ($1, $2, etc.).
Given that you're using C#, you could use the lookaround approach:
Regex r = new Regex(#"(?<!Keep\w*)word(?!\w*Keep)");
s1 = r.Replace(s0, "");
But please don't. There are very few regex flavors that support unrestricted lookbehinds like .NET does, and most problems don't work so neatly as this one anyway.
string str = "Keepword mywordsecond mythirdword myfourthwordKeep";
str = Regex.Replace(str, "(?<!Keep)word", "");
And I'm going to link you to a one of good Regular Expressions Cheat sheet here
This works in notepad++:
(?<!Keep)word(?!Keep)
It uses "look ahead".
You can use negative look-behind assertion if you want to remove all "word" that are not proceeded by "Keep":
String input = "Keepword mywordsecond mythirdword myfourthwordKeep";
String pattern = "(?<!Keep)word";
String output = Regex.Replace(input, pattern, "");
Been scratching my head all day about this one!
Ok, so I have a string which contains the following:
?\"width=\"1\"height=\"1\"border=\"0\"style=\"display:none;\">');
I want to convert that string to the following:
?\"width=1height=1border=0style=\"display:none;\">');
I could theoretically just do a String.Replace on "\"1\"" etc. But this isn't really a viable option as the string could theoretically have any number within the expression.
I also thought about removing the string "\"", however there are other occurrences of this which I don't want to be replaced.
I have been attempting to use the Regex.Replace method as I believe this exists to solve problems along my lines. Here's what I've got:
chunkContents = Regex.Replace(chunkContents, "\".\"", ".");
Now that really messes things up (It replaces the correct elements, but with a full stop), but I think you can see what I am attempting to do with it. I am also worrying that this will only work for single numbers (\"1\" rather than \"11\").. So that led me into thinking about using the "*" or "+" expression rather than ".", however I foresaw the problem of this picking up all of the text inbetween the desired characters (which are dotted all over the place) whereas I obviously only want to replace the ones with numeric characters in between them.
Hope I've explained that clearly enough, will be happy to provide any extra info if needed :)
Try this
var str = "?\"width=\"1\"height=\"1234\"border=\"0\"style=\"display:none;\">');";
str = Regex.Replace(str , "\"(\\d+)\"", "$1");
(\\d+) is a capturing group that looks for one or more digits and $1 references what the group captured.
This works
String input = #"?\""width=\""1\""height=\""1\""border=\""0\""style=\""display:none;\"">');";
//replace the entire match of the regex with only what's captured (the number)
String result = Regex.Replace(input, #"\\""(\d+)\\""", match => match.Result("$1"));
//control string for excpected result
String shouldBe = #"?\""width=1height=1border=0style=\""display:none;\"">');";
//prints true
Console.WriteLine(result.Equals(shouldBe).ToString());
Edit: Solution by #Heinzi
https://stackoverflow.com/a/1731641/87698
I got two strings, for example someText-test-stringSomeMoreText? and some kind of pattern string like this one {0}test-string{1}?.
I'm trying to extract the substrings from the first string that match the position of the placeholders in the second string.
The resulting substrings should be: someText- and SomeMoreText.
I tried to extract with Regex.Split("someText-test-stringSomeMoreText?", "[.]*test-string[.]*\?". However this doesn't work.
I hope somebody has another idea...
One option you have is to use named groups:
(?<prefix>.*)test-string(?<suffix>.*)\?
This will return 2 groups containing the wanted prefix and the suffix.
var match = Regex.Match("someText-test-stringSomeMoreText?",
#"(?<prefix>.*)test-string(?<suffix>.*)\?");
Console.WriteLine(match.Groups["prefix"]);
Console.WriteLine(match.Groups["suffix"]);
I got a solution, at least its a bit dynamical.
First I split up the pattern string {0}test-string{1}? with
string[] patternElements = Regex.Split(inputPattern, #"(\\\{[a-zA-Z0-9]*\})");
Then I spit up the input string someText-test-stringSomeMoreText? with
string[] inputElements = inputString.Split(patternElements, StringSplitOptions.RemoveEmptyEntries);
Now the inputElements are the text pieces corresponding to the placeholders {0},{1},...
I want to capture everything up to (not including) a # sign in a string. The # character may or may not be present (if it's not present, the whole string should be captured).
What would the RegEx and C# code for this by? I've tried: ([^#]+)(?:#) but it doesn't seem to work.
Not a regex but an alternative to try. A regex can be used though, but for this particular situation I prefer this method.
string mystring = "DFASDFASFASFASFAF#322323";
int length = (mystring.IndexOf('#') == -1) ? mystring.Length : mystring.IndexOf('#');
string new_mystring = mystring.Substring(0, length);
Try:
.*(?=#)
I think that should work
EDIT:
^[^#]*
In code:
string match = Regex.Match(input,"^[^#]*").Value;
What's wrong with something as simple as:
[^#]*
Just take the first match?
I have a string similar to
'l','e','t','t','e','r','s'
or
('l','e','t','t','e','r','s')
I know this should be very easy but i dont know how. I know replacing ' and , with "" is an option since both are illegal characters in the result string but i feel theres a better way to do this.
What is the easist way in C# .NET
That depends what exactly your input-format is.
If you have a string which looks like this, you can either use a chained-Replace:
result = "('l','e','t','t','e','r','s')".Replace("(", String.Empty).Replace("'", String.Empty);
or Regular Expressions to remove everything you did not want (in this case everything that is not a lower or uppercase letter:
result = RegEx.Replace("('l','e','t','t','e','r','s')", "[^a-zA-Z]+", String.Empty);
Even easier is to use one of the Constructors of the String, which accepts Character-Arrays:
result = new String(new Char[] {'l','e','t','t','e','r','s'});
Unless performance is critical, you're probably best of just using simple replacement. The shortest replacement you can write is something along the lines of:
string output = Regex.Replace(input, "\W+", "");
Note that \W will not remove underscores or numbers. For keeping English letters only, you would use:
string output = Regex.Replace(input, "[^a-zA-Z]+", "");
Well, I think just doing a replace of '/, characters with "" is the best solution, but if you like needlessly complicating things for the sake of premature optimization you could do a regex match on alphabetic characters and then concatenate all the matches together.
Try using RegEx (System.Text.RegularExpressions).
it seems you want to strip out only the alphabetic characters
public static string StripNonAlphabets(string input)
{
Regex reg = new Regex("[^A-Za-z]");
return reg.Replace(str, string.Empty);
}
this method should return what you're looking for