I need a regular expression to basically get the first part of a string, before the first slash ().
For example in the following:
C:\MyFolder\MyFile.zip
The part I need is "C:"
Another example:
somebucketname\MyFolder\MyFile.zip
I would need "somebucketname"
I also need a regular expression to retrieve the "right hand" part of it, so everything after the first slash (excluding the slash.)
For example
somebucketname\MyFolder\MyFile.zip
would return
MyFolder\MyFile.zip.
You don't need a regular expression (it would incur too much overhead for a simple problem like this), try this instead:
yourString = yourString.Substring(0, yourString.IndexOf('\\'));
And for finding everything after the first slash you can do this:
yourString = yourString.Substring(yourString.IndexOf('\\') + 1);
This problem can be handled quite cleanly with the .NET regular expression engine. What makes .NET regular expressions really nice is the ability to use named group captures.
Using a named group capture allows you to define a name for each part of regular expression you are interested in “capturing” that you can reference later to get at its value. The syntax for the group capture is "(?xxSome Regex Expressionxx). Remember also to include the System.Text.RegularExpressions import statement when using regular expression in your project.
Enjoy!
//Regular expression
string _regex = #"(?<first_part>[a-zA-Z:0-9]+)\\{1}(?<second_part>(.)+)";
//Example 1
{
Match match = Regex.Match(#"C:\MyFolder\MyFile.zip", _regex, RegexOptions.IgnoreCase);
string firstPart = match.Groups["first_part"].Captures[0].Value;
string secondPart = match.Groups["second_part"].Captures[0].Value;
}
//Example 2
{
Match match = Regex.Match(#"somebucketname\MyFolder\MyFile.zip", _regex, RegexOptions.IgnoreCase);
string firstPart = match.Groups["first_part"].Captures[0].Value;
string secondPart = match.Groups["second_part"].Captures[0].Value;
}
You are aware that .NET's file handling classes do this a lot more elegantly, right?
For example in your last example, you could do:
FileInfo fi = new FileInfo(#"somebucketname\MyFolder\MyFile.zip");
string nameOnly = fi.Name;
The first example you could do:
FileInfo fi = new FileInfo(#"C:\MyFolder\MyFile.zip");
string driveOnly = fi.Root.Name.Replace(#"\", "");
This matches all non \ chars
[^\\]*
Here is the regular expression solution using the "greedy" operator '?'...
var pattern = "^.*?\\\\";
var m = Regex.Match("c:\\test\\gimmick.txt", pattern);
MessageBox.Show(m.Captures[0].Value);
Split on slash, then get first item
words = s.Split('\\');
words[0]
Related
I want to use regex to get a filename without extension. I'm having trouble getting regex to return a value. I have this:
string path = #"C:\PERSONAL\TEST\TESTFILE.PDF";
var name = Regex.Match(path, #"(.+?)(\.[^\.]+$|$)").Value;
In this case, name always comes back as C:\PERSONAL\TEST\TESTFILE.PDF. What am I doing wrong, I think my search pattern is correct?
(I am aware that I could use Path.GetFileNameWithoutExtension(path);but I specifically want to try using regex)
You need Group[1].Value
string path = #"C:\PERSONAL\TEST\TESTFILE.PDF";
var match = Regex.Match(path, #"(.+?)(\.[^\.]+$|$)");
if(match.Success)
{
var name = match.Groups[1].Value;
}
match.Value returns the Captures.Value which is the entire match
match.Group[0] always has the same value as match.Value
match.Group[1] return the first capture value
For example:
string path = #"C:\PERSONAL\TEST\TESTFILE.PDF";
var match = Regex.Match(path, #"(.+?)(\.[^\.]+$|$)");
if(match.Success)
{
Console.WriteLine(match.Value);
// return the substring of the matching part
//Output: C:\\PERSONAL\\TEST\\TESTFILE.PDF
Console.WriteLine(match.Groups[0].Value)
// always the same as match.Value
//Output: C:\\PERSONAL\\TEST\\TESTFILE.PDF
Console.WriteLine(match.Groups[1].Value)
// return the first capture group which is (.+?) in this case
//Output: C:\\PERSONAL\\TEST\\TESTFILE
Console.WriteLine(match.Groups[2].Value)
// return the second capture group which is (\.[^\.]+$|$) in this case
//Output: .PDF
}
Since the data is on the right side of the string, tell the regex parser to work from the end of the string to the beginning by using the option RightToLeft. Which will significantly reduce the processing time as well as lessen the actual pattern needed.
The pattern below reads from left to right and says, give me everything that is not a \ character (to consume/match up to the slash and not proceed farther) and start consuming up to a period.
Regex.Match(#"C:\PERSONAL\TEST\TESTFILE.PDF",
#"([^\\]+)\.",
RegexOptions.RightToLeft)
.Groups[1].Value
Prints out
TESTFILE
Try this:
.*(?=[.][^OS_FORBIDDEN_CHARACTERS]+$)
For Windows:
OS_FORBIDDEN_CHARACTERS = :\/\\\?"><\|
this is a sleight modification of:
Regular expression get filename without extention from full filepath
If you are fine to match forbidden characters then simplest regex would be:
.*(?=[.].*$)
Can be a bit shorter and greedier:
var name = Regex.Replace(#"C:\PERS.ONAL\TEST\TEST.FILE.PDF", #".*\\(.*)\..*", "$1"); // "TEST.FILE"
I have a string, for example
<#String1#> + <#String2#> , <#String3#> --<#String4#>
And I want to use regex/string manipulation to get the following result:
<#String1#>,<#String2#>,<#String3#>,<#String4#>
I don't really have any experience doing this, any tips?
There are multiple ways to do something like this, and it depends on exactly what you need. However, if you want to use a single regex operation to do it, and you only want to fix stuff that comes between the bracketed strings, then you could do this:
string input = "<#String1#> + <#String2#> , <#String3#> --<#String4#>";
string pattern = "(?<=>)[^<>]+(?=<)";
string replacement = ",";
string result = Regex.Replace(input, pattern, replacement);
The pattern uses [^<>]+ to match any non-pointy-bracket characters, but it combines it with a look-behind statement ((?<=>)) and a look-ahead statement (?=<) to make sure that it only matches text that occurs between a closing and another opening set of brackets.
If you need to remove text that comes before the first < or after the last >, or if you find the look-around statements confusing, you may want to consider simply matching the text that comes between the brackets and then loop through all the matches and build a new string yourself, rather than using the RegEx.Replace method. For instance:
string input = "sdfg<#String1#> + <#String2#> , <#String3#> --<#String4#>ag";
string pattern = #"<[^<>]+>";
List<String> values = new List<string>();
foreach (Match m in Regex.Matches(input, pattern))
values.Add(m.Value);
string result = String.Join(",", values);
Or, the same thing using LINQ:
string input = "sdfg<#String1#> + <#String2#> , <#String3#> --<#String4#>ag";
string pattern = #"<[^<>]+>";
string result = String.Join(",", Regex.Matches(input, pattern).Cast<Match>().Select(x => x.Value));
If you're just after string manipulation and don't necessarily need a regex, you could simply use the string.Replace method.
yourString = yourString.Replace("#> + <#", "#>,<#");
I have following string
string s=#"\Users\Public\Roaming\Intel\Wireless\Settings";
I want output string like
string output="Wireless";
Sub-string what I want should be after "Intel\" and it should ends with the first "\" after "Intel\" before string Intel and after Intel the string may be different.
I have achieved it using string.substring() but I want to get it using regular expression ? what regular expression should I write to get that string.
For a regex solution you may use:
(?<=intel\\)([^\\]+?)[\\$]
Demo
Notice the i flag.
BTW, Split is much simpler and faster solution than regexes. Regex is associated with patterns of string. For a static/fixed string structure, it is a wise solution to manipulate it with string functions.
With regex, it will look like
var txt = #"\Users\Public\Roaming\Intel\Wireless\Settings";
var res = Regex.Match(txt, #"Intel\\([^\\]+)", RegexOptions.IgnoreCase).Groups[1].Value;
But usually, you should use string methods with such requirements. Here is a demo code (without error checking):
var strt = txt.IndexOf("Intel\\") + 6; // 6 is the length of "Intel\"
var end = txt.IndexOf("\\", strt + 1); // Look for the next "\"
var res2 = txt.Substring(strt, end - strt); // Get the substring
See IDEONE demo
You could also use this if you want everything AFTER the intel/
/(?:intel\\)((\w+\\?)+)/gi
http://regexr.com/3blqm
You would need the $1outcome. Note that $1 will be empty or none existent if the string does not contain Intel/ or anything after it.
Why not use Path.GetDirectoryName and Path.GetFileName for this:
string s = #"\Users\Public\Roaming\Intel\Wireless\Settings";
string output = Path.GetFileName(Path.GetDirectoryName(s));
Debug.Assert(output == "Wireless");
It is possible to iterate over directory components until you find the word Intel and return the next component.
i have this string:
"Network adapter 'Realtek PCIe GBE Family Controller' on local host"
what will be the best way to return only the string between "'" ? (Realtek PCIe GBE Family Controller)
If you're comfortable with regular expressions, you could use a pattern like:
/'[^']*'/
to capture everything between the single quotes
You can use regular expressions, like this:
var s = "hello 'world' hehe";
var m = Regex.Match(s, "'([^']*)'");
string res = null;
if (m.Success) {
res = m.Groups[1].ToString();
}
Console.WriteLine(res);
The key to the solution is this regular expression:
'([^']*)'
It starts the match when it finds a single quote, and continues until it finds the closing quote, capturing everything in between. The captured group is then retrieved through the Regex API. Note that the capturing groups that you define start at index 1; index zero is reserved to mean "the entire match".
Take a look at the demo on ideone.
You can use the Substring() method to chop it up.
tempStr = str.Substring(str.IndexOf("'")+1);
yourStr = tempStr.SubString(0, tempStr.IndexOf("'"));
I have string. "12341234115151_log_1.txt" (this string length is not fixed. but "log" pattern always same)
I have a for loop.
each iteration, I want to set the number after "log" of i.
like "12341234115151_log_2.txt"
"12341234115151_log_3.txt"
....
to
"12341234115151_log_123.txt"
in c#, what is a good way to do so?
thanks.
A regex is ideal for this. You can use the Regex.Replace method and use a MatchEvaluator delegate to perform the numerical increment.
string input = "12341234115151_log_1.txt";
string pattern = #"(\d+)(?=\.)";
string result = Regex.Replace(input, pattern,
m => (int.Parse(m.Groups[1].Value) + 1).ToString());
The pattern breakdown is as follows:
(\d+): this matches and captures any digit, at least once
(?=\.): this is a look-ahead which ensures that a period (or dot) follows the number. A dot must be escaped to be a literal dot instead of a regex metacharacter. We know that the value you want to increment is right before the ".txt" so it should always have a dot after it. You could also use (?=\.txt) to make it clearer and be explicit, but you may have to use RegexOptions.IgnoreCase if your filename extension can have different cases.
You can use Regex. like this
var r = new Regex("^(.*_log_)(\\d).txt$")
for ... {
var newname = r.Replace(filename, "${1}"+i+".txt");
}
Use regular expressions to get the counter, then just append them together.
If I've read your question right...
How about,
for (int i =0; i<some condition; i++)
{
string name = "12341234115151_log_"+ i.ToString() + ".txt";
}