How to Split a String in C# Using Regex to Handle Commas Within Quotes?

Using regular expressions to split strings in C#: processing commas within quotes

In various scenarios such as data parsing or SQL string operations, strings containing commas may need to be split using regular expressions. However, challenges arise when commas appear inside and outside quotation marks.

Let us consider the following string:

<code>('ABCDEFG', 123542, 'XYZ 99,9')</code>

Our goal is to split this string into its component parts using regular expressions in order to obtain the following output:

• 'ABCDEFG'
• 123542
• 'XYZ 99,9'

The key is to recognize commas outside quotation marks. For this we can use the powerful regular expression pattern:

<code>",(?=(?:[^']*'[^']*')*[^']*$)"</code>

Let’s break down this pattern:

• ": Matches a literal comma.

• (?=(?:[^']*'[^']*')*[^']*$): This is a lookahead assertion that checks whether a comma is followed by an even number of quotes.

  • (?:[^']*'[^']*')*: Matches any number of pairs of single quotes with the content between them.
  • [^']*$: Matches any character after the last quotation mark, but not including the quotation mark.

By using this pattern we can match any comma that is followed by an even number of quotes, effectively ensuring that we only split the string outside of the quotes.

To use this regular expression for splitting we will use the following C# code:

var result = Regex.Split(samplestring, ",(?=(?:[^']*'[^']*')*[^']*$)");

After executing this code, result will contain an array of strings, each string representing a component of the original string, split according to the desired conditions.

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