String search using regular expressions

Question

i am trying to match strings that dont contain quotation marks but they can contain escaped quotation marks.

when i say string i mean quotation marks and a string inside them.

i am using this regular expression but it does not work.

\"(?![^\\\\]\")\"

solution:

@"""[^""\\\r\n]*(?:\\.[^""\\\r\n]*)*"""

the code (c#)

MatchCollection matches = Regex.Matches(input,@"""[^""\\\r\n]*(?:\\.[^""\\\r\n]*)*""");
        foreach (Match match in matches)
        {
            result += match.Index + " " + match.Value + System.Environment.NewLine ;
        }

score 6 · Accepted Answer · edited Jul 07 '11 at 08:34

6

"[^"\\\r\n]*(?:\\.[^"\\\r\n]*)*"

http://www.regular-expressions.info/examplesprogrammer.html

Note that you'll need to escape certain chars properly (depending on what string literal you use)! The following demo:

using System;
using System.Text.RegularExpressions;

class Program
{
  static void Main()
  {
    string input = "foo \"some \\\" text\" bar";

    Match match = Regex.Match(input, @"""[^""\\\r\n]*(?:\\.[^""\\\r\n]*)*""");

    if (match.Success)
    {
      Console.WriteLine(input);
      Console.WriteLine(match.Groups[0].Value);
    }
  }
}

will print:

foo "some \" text" bar
"some \" text"

edited Jul 07 '11 at 08:34

Bart Kiers

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answered Jul 07 '11 at 08:20

Kirill Polishchuk

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1

@jaywayco, Post non matched examples – Kirill Polishchuk Jul 07 '11 at 08:25
it should match this blah\"blah and not this blah"blah – jaywayco Jul 07 '11 at 08:31
@polishchuk, I took the liberty to add an example based on the (working!) regex. – Bart Kiers Jul 07 '11 at 08:35
@jaywayco, Check, it will match `"blah\"blah"` and `"blah"` from `"blah"blah"`, if you wanna to validate string input, just put `^` at start and `$` at end, e.g.: `^"[^"\\\r\n]*(?:\\.[^"\\\r\n]*)*"$`, so it will match `"blah\"blah"`, but not `"blah"blah"`. – Kirill Polishchuk Jul 07 '11 at 08:35
for it to work in c# it need to be \"[^\"\\\r\n]*(?:\\.[^\"\\\r\n]*)*\" – yossi Jul 07 '11 at 09:15
1

@yossi, it depends on the string literal you choose. You only need to escape the `"` by adding another `"` in front of it when using the `@"..."` literal, as can be seen by running the demo. – Bart Kiers Jul 07 '11 at 09:20

score 2 · Answer 2 · edited Jul 07 '11 at 08:35

2

Try this

[^"\\]*(?:\\.[^"\\]*)*

edited Jul 07 '11 at 08:35

Bart Kiers

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answered Jul 07 '11 at 08:30

SMK

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String search using regular expressions

2 Answers2