Trim characters from string

Question

I am trying to extract characters from a string. I want [a-z or A-Z or 0-9 or . or _] all other characters should be trimmed from the string.

I have a regular expression that can replace characters but I want other way around, I want a regular expression or any other method that allows only [a-z or A-Z or 0-9 or . or _] and remove all other characters.

What was the problem with it then ? You can do it easily with regex ? what actually is the problem you faced ? — Code Cooker, May 09 '17 at 05:15
What is the difference in Replacing characters or matching when using RegEx? — sachin, May 09 '17 at 05:15
Does `Regex.Replace(text, "[^a-zA-Z0-9 _]", "")` work for you? — Enigmativity, May 09 '17 at 05:16
Regex.Replace(text, "[^a-zA-Z0-9 _]", "") is replacing a-zA-Z0-9 _ with empty string and returning me characters which I don't want. I want other way around, I want only a-zA-Z0-9 _ and all other characters should be removed. — Ali, May 09 '17 at 05:23
@Ali - You should try this code. Running `Regex.Replace("g%4 D-u!!u_e", "[^a-zA-Z0-9 _]", "")` returns `"g4 Duu_e"`. Isn't that what you want? — Enigmativity, May 09 '17 at 05:24
@Ali - the `^` after the `[` says "not the following characters". — Enigmativity, May 09 '17 at 05:26

score 0 · Answer 1 · answered May 09 '17 at 05:25

0

Try this simple function. This will just keep the correct characters.

    private string ClearUp(string inData) {
        var reg = new Regex("[^A-Za-z0-9._]");

        return reg.Replace(inData, string.Empty);
    }

answered May 09 '17 at 05:25

MrApnea

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sachin · Accepted Answer · 2017-05-09T05:35:48.340

Use the RegEx pattern [^\w.] to extract only a-z, A-Z, 0-9, _ or .

var cleanedString = Regex.Replace("yourstring", @"[^\w.]", string.Empty);

Here is the explanation:

\w represents a-z, A-Z, 0-9 or _
The . after \w would allow for literal '.'
The ^ at start means everything except what follows
RegEx.Replace would Replace any occurrence of unwanted characters (specified by pattern in second parameter) from supplied input (first parameter) with empty string (specified by the last parameter)

Trim characters from string

2 Answers2