Substring \ in C#

Question

I am trying to substring but getting exception throwing.

 my string  "currentUserLogin" is uponet\\xyz

so what I want final result is xyz

string currentUser = currentUserLogin.Substring(currentUserLogin.LastIndexOf("'\'"));

What exception are you getting? Why don' t you post it here? — Alpay, Sep 30 '15 at 14:24
it doesn't work with single! i guess that is why is throwing error — K.Z, Sep 30 '15 at 14:24
"It doesn't work" doesn't explain what problem you're seeing in that case *or* what problem you're seeing now... — Jon Skeet, Sep 30 '15 at 14:25

MarkPflug · Answer 1 · 2015-09-30T14:38:10.103

3

Try:

string currentUser = currentUserLogin.Substring(currentUserLogin.LastIndexOf("\\") + 1);

I should also point out that you will want some actual error handling. This will throw an IndexOutOfRangeException if the \ comes at the very end of the string.

Relevant documentation: https://msdn.microsoft.com/en-us/library/aa691090(v=vs.71).aspx

edited Sep 30 '15 at 14:38

answered Sep 30 '15 at 14:24

MarkPflug

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that returns a \xyz wierd, since we ask for the last ? – Sep 30 '15 at 14:36
Cool :) and no, no error just tested, indexes is zero based so and the substring is not, it uses the actual posiotion in the string 1,2,3 etc. so adding the 1 effectively converts it :) ... just had to test it my self – Sep 30 '15 at 14:48

Philippe Paré · Answer 2 · 2015-09-30T15:07:31.207

2

Safer way to do it is to check if it is in the string first, or check if index > -1.

int index = currentUserLogin.LastIndexOf('\\');
if (index > -1)
{
    if (index + 1 == currentUserLogin)
    {
        currentUser = string.Empty;
    }
    else
    {
        currentUser = currentUserLogin.SubString(index + 1);
    }
}

edited Sep 30 '15 at 15:07

answered Sep 30 '15 at 14:42

Philippe Paré

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This solution is probably more desirable than catching an exception. There is overhead that comes with exception handling. See post on C# try/catch overhead: http://stackoverflow.com/questions/52312/what-is-the-real-overhead-of-try-catch-in-c – iCode Sep 30 '15 at 14:50
This will still throw an exception if the \ is at the end of the string. – MarkPflug Sep 30 '15 at 14:52
True, I'll add a test for this – Philippe Paré Sep 30 '15 at 15:06

score 1 · Answer 3 · answered Sep 30 '15 at 14:32

This here works like a charm

        string currentUserLogin = "uponet\\xyz"; //Login
        string[] currentUserParts = currentUserLogin.Split('\\');// splits in parts of [uponet],[],[xyz]
        string currentUser = currentUserParts[currentUserParts.Count() - 1]; // get last from array

\ is a escape charector so by it standing a lone the compiler dont know what to do with it, the correct way to use e.g:

\r that is a new line
\\ that translate to \

and so forth

Hope this helps :)

Substring \ in C#

3 Answers3