How can I remove quoted string literals from a string in C#?

Question

I have a string:

Hello "quoted string" and 'tricky"stuff' world

and want to get the string minus the quoted parts back. Eg,

Hello and world

Any suggestions?

Answer 1

resultString = Regex.Replace(subjectString, 
    @"([""'])# Match a quote, remember which one
    (?:      # Then...
     (?!\1)  # (as long as the next character is not the same quote as before)
     .       # match any character
    )*       # any number of times
    \1       # until the corresponding closing quote
    \s*      # plus optional whitespace
    ", 
    "", RegexOptions.IgnorePatternWhitespace);

will work on your example.

resultString = Regex.Replace(subjectString, 
    @"([""'])# Match a quote, remember which one
    (?:      # Then...
     (?!\1)  # (as long as the next character is not the same quote as before)
     \\?.    # match any escaped or unescaped character
    )*       # any number of times
    \1       # until the corresponding closing quote
    \s*      # plus optional whitespace
    ", 
    "", RegexOptions.IgnorePatternWhitespace);

will also handle escaped quotes.

So it will correctly transform

Hello "quoted \"string\\" and 'tricky"stuff' world

into

Hello and world

Answer 2

Use a regular expression to match any quoted strings with the string and replace them with the empty string. Use the Regex.Replace() method to do the pattern matching and replacement.

Answer 3

In case, like me, you're afraid of regex, I've put together a functional way to do it, based on your example string. There's probably a way to make the code shorter, but I haven't found it yet.

private static string RemoveQuotes(IEnumerable<char> input)
{
    string part = new string(input.TakeWhile(c => c != '"' && c != '\'').ToArray());
    var rest = input.SkipWhile(c => c != '"' && c != '\'');
    if(string.IsNullOrEmpty(new string(rest.ToArray())))
        return part;
    char delim = rest.First();
    var afterIgnore = rest.Skip(1).SkipWhile(c => c != delim).Skip(1);
    StringBuilder full = new StringBuilder(part);
    return full.Append(RemoveQuotes(afterIgnore)).ToString();
}