How to split strings using regular expressions

Question

I want to split a string into a list or array.

Input: green,"yellow,green",white,orange,"blue,black"

The split character is the comma (,), but it must ignore commas inside quotes.

The output should be:

• green
• yellow,green
• white
• orange
• blue,black

Thanks.

Answer 1

Actually this is easy enough to just use match :

string subjectString = @"green,""yellow,green"",white,orange,""blue,black""";
try
{
    Regex regexObj = new Regex(@"(?<="")\b[a-z,]+\b(?="")|[a-z]+", RegexOptions.IgnoreCase);
    Match matchResults = regexObj.Match(subjectString);
    while (matchResults.Success)
    {
        Console.WriteLine("{0}", matchResults.Value);
        // matched text: matchResults.Value
        // match start: matchResults.Index
        // match length: matchResults.Length
        matchResults = matchResults.NextMatch();
    }
}

Output :

green
yellow,green
white
orange
blue,black

Explanation :

@"
             # Match either the regular expression below (attempting the next alternative only if this one fails)
   (?<=         # Assert that the regex below can be matched, with the match ending at this position (positive lookbehind)
      ""            # Match the character “""” literally
   )
   \b           # Assert position at a word boundary
   [a-z,]       # Match a single character present in the list below
                   # A character in the range between “a” and “z”
                   # The character “,”
      +            # Between one and unlimited times, as many times as possible, giving back as needed (greedy)
   \b           # Assert position at a word boundary
   (?=          # Assert that the regex below can be matched, starting at this position (positive lookahead)
      ""            # Match the character “""” literally
   )
|            # Or match regular expression number 2 below (the entire match attempt fails if this one fails to match)
   [a-z]        # Match a single character in the range between “a” and “z”
      +            # Between one and unlimited times, as many times as possible, giving back as needed (greedy)
"