String Replace not work

Question

I have a string (an example of its value is {"id":"123241077871_4423423423414"}) and I only require the part with the numbers and the underscore. However, my way of doing it with the String.Replace method doesn't work. Can anyone help me?

This is what I've tried:

Settings.Default["lastid"].ToString().Replace('{"id":"'+"}',null);

Well that's invalid C# to start with, so you should be getting a compile-time error... It's not a valid string literal. I would suggest avoiding direct string manipulation here anyway - just parse it as JSON and use the parsed value. — Jon Skeet, May 19 '13 at 17:16
And for future reference your questions should expand on the way in which something doesn't work. Wrong result? Compiler error? Runtime error? etc. — Chris, May 19 '13 at 17:20

Mike Precup · Accepted Answer · 2013-05-19T17:41:43.103

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Your code should be

Settings.Default["lastid"].ToString().Replace("{\"id\":\"", "").Replace("\"}","");

As Jon Skeet said, currently, it's not a valid string literal. In addition, Replace only searches for one string of text. You can't do both of them in one pass.

edited May 19 '13 at 17:41

answered May 19 '13 at 17:18

Mike Precup

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That's a fairly intense way of pointing out an extra semicolon. Fixed. – Mike Precup May 19 '13 at 17:42

score 1 · Answer 2 · answered May 19 '13 at 17:31

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How about using a real json parser and doing it the right way

var id = JsonConvert.DeserializeAnonymousType(s, new { id = "" }).id;

answered May 19 '13 at 17:31

I4V

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Saman Gholami · Answer 3 · 2013-05-19T17:33:27.103

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Change your code to this :

Settings.Default["lastid"].ToString().Replace("{\"id\":","");
Settings.Default["lastid"].ToString().Replace("\"}\"","");

edited May 19 '13 at 17:33

answered May 19 '13 at 17:18

Saman Gholami

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Your code won't remove the opening and closing quotes around the 123241077871_4423423423414. – Mike Precup May 19 '13 at 17:21

Steve · Answer 4 · 2013-05-19T17:40:18.027

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Just in one pass with regex

string test = Settings.Default["lastid"].ToString();
string result = Regex.Replace(test, @"[^0-9_]", @"");
Console.WriteLine(result);

The regex pattern means:

match any character NOT included (^) inside the brackets
and replace it with an empty string.

As noted by @newStackExchangeInstance in the comments below, the pattern [^0-9_] could be changed in [^\d_] to keep excluded from the replacement also other Unicode Numerical Characters

edited May 19 '13 at 17:40

answered May 19 '13 at 17:23

Steve

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Use `[^\d_]` instead. It's better, as it means if he gets some unicode numerical chars, they still count as numbers and are not replaced. – It'sNotALie. May 19 '13 at 17:30
@newStackExchangeInstance Sorry, I am not aware of this. Could you point me to an example? – Steve May 19 '13 at 17:32
http://stackoverflow.com/questions/6479423/does-d-in-regex-mean-a-digit Look at the top answer. (Sidenote: I know it says python, but it applies to C# as well) – It'sNotALie. May 19 '13 at 17:34
@newStackExchangeInstance well, good to know, not of immediate usage for me, but thanks. I will fix my answer with your findings – Steve May 19 '13 at 17:37

score 0 · Answer 5 · answered May 19 '13 at 17:28

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Try using Regex.

string json = @"{""id"":""123241077871_4423423423414""}" //or whatever your value is
Regex.Match(json, @"{""id"":""(\d+_\d+)""}".Groups[1] //will give you your result

answered May 19 '13 at 17:28

It'sNotALie.

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String Replace not work

5 Answers5