How to convert camel case to snake case with two capitals next to each other

Question

I am trying to convert camel case to snake case.

Like this:

"LiveKarma" -> "live_karma"
"youGO" -> "you_g_o"

I cannot seem to get the second example working like that. It always outputs as 'you_go' . How can I get it to output 'you_g_o'

My code:

(Regex.Replace(line, "(?<=[a-z0-9])[A-Z]", "_$0", RegexOptions.Compiled)).ToLowerInvariant()

Answer 1

Here is an extension method that transforms the text into a snake case:

using System.Text;

public static string ToSnakeCase(this string text)
{
    if(text == null) {
        throw new ArgumentNullException(nameof(text));
    }
    if(text.Length < 2) {
        return text;
    }
    var sb = new StringBuilder();
    sb.Append(char.ToLowerInvariant(text[0]));
    for(int i = 1; i < text.Length; ++i) {
        char c = text[i];
        if(char.IsUpper(c)) {
            sb.Append('_');
            sb.Append(char.ToLowerInvariant(c));
        } else {
            sb.Append(c);
        }
    }
    return sb.ToString();
}

Put it into a static class somewhere (named for example StringExtensions) and use it like this:

string text = "LiveKarma";
string snakeCaseText = text.ToSnakeCase();
// snakeCaseText => "live_karma"