I have following string:
string source = "Test/Company/Business/Department/Logs.tvs/v1";
The / character is the separator between various elements in the string. I need to get the last two elements of the string. I have following code for this purpose. This works fine. Is there any faster/simpler code for this?
CODE
static void Main()
{
string component = String.Empty;
string version = String.Empty;
string source = "Test/Company/Business/Department/Logs.tvs/v1";
if (!String.IsNullOrEmpty(source))
{
String[] partsOfSource = source.Split('/');
if (partsOfSource != null)
{
if (partsOfSource.Length > 2)
{
component = partsOfSource[partsOfSource.Length - 2];
}
if (partsOfSource.Length > 1)
{
version = partsOfSource[partsOfSource.Length - 1];
}
}
}
Console.WriteLine(component);
Console.WriteLine(version);
Console.Read();
}
Why no regular expression? This one is fairly easy:
.*/(?<component>.*)/(?<version>.*)$
You can even label your groups so for your match all you need to do is:
component = myMatch.Groups["component"];
version = myMatch.Groups["version"];
The following should be faster, as it only scans as much of the string as it needs to to find two / and it doesn't bother splitting up the whole string:
string component = "";
string version = "";
string source = "Test/Company/Business/Department/Logs.tvs/v1";
int last = source.LastIndexOf('/');
if (last != -1)
{
int penultimate = source.LastIndexOf('/', last - 1);
version = source.Substring(last + 1);
component = source.Substring(penultimate + 1, last - penultimate - 1);
}
That said, as with all performance questions: profile! Try the two side-by-side with a big list of real-life inputs and see which is fastest.
(Also, this will leave empty strings rather than throw an exception if there is no slash in the input... but throw if source is null, lazy me.)
Your approach is the most suitable one given that your are looking for substrings at a particular index. A LINQ expression to do the same in this case will likely not improve the code or its readability.
For reference, there is some great information from Microsoft here on working with strings and LINQ. In particular see the article here which covers some examples with both LINQ and RegEx.
EDIT: +1 For Matt's named group within RegEx approach... that's the nicest solution I've seen.
Your code mostly looks fine. A couple of points to note:
String.Split() will never return null, so you don't need the null check on it.
If the source string has fewer than two / characters, how would you deal with that? (The Original Post was updated to address this)
Do you really want to just output empty strings if your source string is null or empty (or invalid)? If you have specific expectations about the nature of the input, you may want to consider failing fast when those expectations are not met.
You could try something like this but I doubt it would be much faster. You could do some meassurements with System.Diagnostics.StopWatch to see if you feel the need.
string source = "Test/Company/Business/Department/Logs.tvs/v1";
int index1 = source.LastIndexOf('/');
string last = source.Substring(index1 + 1);
string substring = source.Substring(0, index1);
int index2 = substring.LastIndexOf('/');
string secondLast = substring.Substring(index2 + 1);
I would try
string source = "Test/Company/Business/Department/Logs.tvs/v1";
var components = source.Split('/').Reverse().Take(2);
String last = string.Empty;
var enumerable = components as string[] ?? components.ToArray();
if (enumerable.Count() == 2)
last = enumerable.FirstOrDefault();
var secondLast = enumerable.LastOrDefault();
Hope this will help
you can retrieve the last two words using the process as below:
string source = "Test/Company/Business/Department/Logs.tvs/v1";
String[] partsOfSource = source.Split('/');
if(partsOfSourch.length>2)
for(int i=partsOfSourch.length-2;i<=partsOfSource.length-1;i++)
console.writeline(partsOfSource[i]);
Related
I have such a comic string.
www.asdsad.de/dsfdsf/sdfdsf=dsfdsfs?dsfsndfsajdn=sfdjasdhads=test.xlsx
I would like to get only the test.xlsx out.
So I wanted to say that I wanted to separate the string from behind.
That he he once the first = sign found me the string supplies the from the end to the = sign goes.
Whats the best way to do this?
Unfortunately, I would not know how I should do with SubString, since the length can always be different. But I know that in the end is what I need and the unnecessary with the first = Begin from behind
Yes, Substring will do, and there's no need to know the length:
string source = "www.asdsad.de/dsfdsf/sdfdsf=dsfdsfs?dsfsndfsajdn=sfdjasdhads=test.xlsx";
// starting from the last '=' up to the end of the string
string result = source.SubString(source.LastIndexOf("=") + 1);
Another option:
string source = "www.asdsad.de/dsfdsf/sdfdsf=dsfdsfs?dsfsndfsajdn=sfdjasdhads=test.xlsx";
Stack<char> sb = new Stack<char>();
for (var i = source.Length - 1; i > 0; i--)
{
if (source[i] == '=')
{
break;
}
sb.Push(source[i]);
}
var result = string.Concat(sb.ToArray());
I have a file called file_test1.txt and I want to extract just test1 from the name and place it in a string. Whats the best way of doing this?
E.g.
string fullfile = #"C:\file_test1.txt";
string section = [test1] from fullfile; // <- expected result
I want to be able to split on 'file_' and '.txt' as the 'test1' section could be larger or smaller however the 'file_' and '.txt' will always be the same.
Try Path.GetFileNameWithoutExtension(fullfile).Substring(5) (or Substring("TEMPLATE_PREFIX".Length))
You can try spilt
var test = Path.GetFileNameWithoutExtension(fullfile).split('_')[1];
Try following
string fullfile = #"C:\file_test1.txt";
var name = fullfile.Substring(8,fullfile.Length-12)
As c:\file_ and .txt are fixed, You can take Substring starting at index 8 (skip leading name), upto length of total string length - 12 (12 => length of leading name, and trailing extension)
Thought I'd give a solution that uses Split and handles files with multiple underscores:
string.Join("_", Path.GetFileNameWithoutExtension(file).Split('_').Skip(1));
String.Split() works quite well for my uses:
http://msdn.microsoft.com/en-us/library/b873y76a.aspx
Obviously many ways to accomplish this. Here's yet another approach:
string fullfile = #"C:\file_test1.txt";
int index1 = fullfile.LastIndexOf("file_");
if (index1 != -1)
{
int index2 = fullfile.IndexOf(".", index1);
if (index2 != -1)
{
string section = fullfile.Substring(index1 + 5, index2 - index1 - 5);
}
}
You could also get "test1", or any subsequent filename (assuming your file naming convention remains constant!) using this regular expression:
var defaultRegex = new Regex(#"(?<=_).*(?=.txt)");
var matches = defaultRegex.Matches(fullfile);
var match = matches[0].Value;
The regular expression:
(?<=_).*(?=.txt)
uses positive look behind to find text preceded by '_', and also positive lookahead to find text which has '.txt' ahead of it.
I am trying to process a report from a system which gives me the following code
000=[GEN] OK {Q=1 M=1 B=002 I=3e5e65656-e5dd-45678-b785-a05656569e}
I need to extract the values between the curly brackets {} and save them in to variables. I assume I will need to do this using regex or similar? I've really no idea where to start!! I'm using c# asp.net 4.
I need the following variables
param1 = 000
param2 = GEN
param3 = OK
param4 = 1 //Q
param5 = 1 //M
param6 = 002 //B
param7 = 3e5e65656-e5dd-45678-b785-a05656569e //I
I will name the params based on what they actually mean. Can anyone please help me here? I have tried to split based on spaces, but I get the other garbage with it!
Thanks for any pointers/help!
If the format is pretty constant, you can use .NET string processing methods to pull out the values, something along the lines of
string line =
"000=[GEN] OK {Q=1 M=1 B=002 I=3e5e65656-e5dd-45678-b785-a05656569e}";
int start = line.IndexOf('{');
int end = line.IndexOf('}');
string variablePart = line.Substring(start + 1, end - start);
string[] variables = variablePart.Split(' ');
foreach (string variable in variables)
{
string[] parts = variable.Split('=');
// parts[0] holds the variable name, parts[1] holds the value
}
Wrote this off the top of my head, so there may be an off-by-one error somewhere. Also, it would be advisable to add error checking e.g. to make sure the input string has both a { and a }.
I would suggest a regular expression for this type of work.
var objRegex = new System.Text.RegularExpressions.Regex(#"^(\d+)=\[([A-Z]+)\] ([A-Z]+) \{Q=(\d+) M=(\d+) B=(\d+) I=([a-z0-9\-]+)\}$");
var objMatch = objRegex.Match("000=[GEN] OK {Q=1 M=1 B=002 I=3e5e65656-e5dd-45678-b785-a05656569e}");
if (objMatch.Success)
{
Console.WriteLine(objMatch.Groups[1].ToString());
Console.WriteLine(objMatch.Groups[2].ToString());
Console.WriteLine(objMatch.Groups[3].ToString());
Console.WriteLine(objMatch.Groups[4].ToString());
Console.WriteLine(objMatch.Groups[5].ToString());
Console.WriteLine(objMatch.Groups[6].ToString());
Console.WriteLine(objMatch.Groups[7].ToString());
}
I've just tested this out and it works well for me.
Use a regular expression.
Quick and dirty attempt:
(?<ID1>[0-9]*)=\[(?<GEN>[a-zA-Z]*)\] OK {Q=(?<Q>[0-9]*) M=(?<M>[0-9]*) B=(?<B>[0-9]*) I=(?<I>[a-zA-Z0-9\-]*)}
This will generate named groups called ID1, GEN, Q, M, B and I.
Check out the MSDN docs for details on using Regular Expressions in C#.
You can use Regex Hero for quick C# regex testing.
You can use String.Split
string[] parts = s.Split(new string[] {"=[", "] ", " {Q=", " M=", " B=", " I=", "}"},
StringSplitOptions.None);
This solution breaks up your report code into segments and stores the desired values into an array.
The regular expression matches one report code segment at a time and stores the appropriate values in the "Parsed Report Code Array".
As your example implied, the first two code segments are treated differently than the ones after that. I made the assumption that it is always the first two segments that are processed differently.
private static string[] ParseReportCode(string reportCode) {
const int FIRST_VALUE_ONLY_SEGMENT = 3;
const int GRP_SEGMENT_NAME = 1;
const int GRP_SEGMENT_VALUE = 2;
Regex reportCodeSegmentPattern = new Regex(#"\s*([^\}\{=\s]+)(?:=\[?([^\s\]\}]+)\]?)?");
Match matchReportCodeSegment = reportCodeSegmentPattern.Match(reportCode);
List<string> parsedCodeSegmentElements = new List<string>();
int segmentCount = 0;
while (matchReportCodeSegment.Success) {
if (++segmentCount < FIRST_VALUE_ONLY_SEGMENT) {
string segmentName = matchReportCodeSegment.Groups[GRP_SEGMENT_NAME].Value;
parsedCodeSegmentElements.Add(segmentName);
}
string segmentValue = matchReportCodeSegment.Groups[GRP_SEGMENT_VALUE].Value;
if (segmentValue.Length > 0) parsedCodeSegmentElements.Add(segmentValue);
matchReportCodeSegment = matchReportCodeSegment.NextMatch();
}
return parsedCodeSegmentElements.ToArray();
}
I have the following:
string test = "9586-202-10072"
How would I get all characters to the right of the final - so 10072. The number of characters is always different to the right of the last dash.
How can this be done?
You can get the position of the last - with str.LastIndexOf('-'). So the next step is obvious:
var result = str.Substring(str.LastIndexOf('-') + 1);
Correction:
As Brian states below, using this on a string with no dashes will result in the original string being returned.
You could use LINQ, and save yourself the explicit parsing:
string test = "9586-202-10072";
string lastFragment = test.Split('-').Last();
Console.WriteLine(lastFragment);
I can see this post was viewed over 46,000 times. I would bet many of the 46,000 viewers are asking this question simply because they just want the file name... and these answers can be a rabbit hole if you cannot make your substring verbatim using the at sign.
If you simply want to get the file name, then there is a simple answer which should be mentioned here. Even if it's not the precise answer to the question.
result = Path.GetFileName(fileName);
see https://msdn.microsoft.com/en-us/library/system.io.path.getfilename(v=vs.110).aspx
string tail = test.Substring(test.LastIndexOf('-') + 1);
YourString.Substring(YourString.LastIndexOf("-"));
With the latest C# 8 and later you can use Range Indexer as follows:-
string test = "9586-202-10072"
var foo = test?[(test.LastIndexOf('-') + 1)..];
// foo is => 10072
string atest = "9586-202-10072";
int indexOfHyphen = atest.LastIndexOf("-");
if (indexOfHyphen >= 0)
{
string contentAfterLastHyphen = atest.Substring(indexOfHyphen + 1);
Console.WriteLine(contentAfterLastHyphen );
}
See String.lastIndexOf method
I created a string extension for this, hope it helps.
public static string GetStringAfterChar(this string value, char substring)
{
if (!string.IsNullOrWhiteSpace(value))
{
var index = value.LastIndexOf(substring);
return index > 0 ? value.Substring(index + 1) : value;
}
return string.Empty;
}
test.Substring[(test.LastIndexOf('-') + 1)..]
C# 8 (late 2019) introduces range operator and simplifies it a bit further. The two dots here means from the index (inclusive) till the end of string.
test.Substring(test.LastIndexOf("-"))
and... in case you need the left part of a string:
private string AllTheLeftPart(string theString)
{
string rightPart = theString.Substring(theString.LastIndexOf('-') + 1);
string leftPart theString.Replace("-" + rightPart, String.Empty);
return leftPart ;
}
I want to extract the first folder in the URL below, in this example it is called 'extractThisFolderName' but the folder could have any name and be any length. With this in mind how can I use substring to extract the first folder name?
The string: www.somewebsite.com/extractThisFolderName/leave/this/behind
String folderName = path.Substring(path.IndexOf(#"/"),XXXXXXXXXXX);
It's the length I'm struggling with.
If you're getting a Uri, why not just do uri.Segments[0]?
Or even path.Split(new Char[] { '/' })[1] ?
If you're going to be using each path part, you can use:
String[] parts = path.Split('/');
At which point you can access the "extractThisFolderName" part by accessing parts[1].
Alternatively, you can do this to splice out the foldername:
int firstSlashIndex = path.IndexOf('/');
int secondSlashIndex = path.IndexOf('/', firstSlashIndex + 1);
String folderName = path.Substring(firstSlashIndex + 1, secondSlashIndex - firstSlashIndex);
Daniel's answer gives you other practical ways of doing it. Another alternative using substring:
int start = path.IndexOf('/')+1; // Note that you don't need a verbatim string literal
int secondSlash = path.IndexOf('/', start);
return path.Substring(start, secondSlash-start);
You'll want to add some error checking in there, of course :)
The problem also lends itself to regular expressions. An expression like:
(?<host>.*?)/(?<folder>.*?)/
Is clear about what's going on and you can get the data out by those names.
int start = path.IndexOf('/');
int end = path.IndexOf('/', start + 1);
if (end == -1) end = path.Length;
string folderName = path.Substring(start + 1, end - start - 1);
EDIT: Daniel Schaffer's answer about using uri segments is preferable, but left this in as it may be your path is not really a valid uri.
You could do:
string myStr = "www.somewebsite.com/extractThisFolderName/leave/this/behind";
int startIndex = myStr.IndexOf('/') + 1;
int length = myStr.IndexOf('/', startIndex) - startIndex;
Console.WriteLine(myStr.Substring(startIndex, length));
At the same point I assume this is being done in ASP.Net if so I think there might be another way to get this without doign the querying.
folderName.Split('/')[1]