Regular expression, split string by capital letter but ignore TLA

Question

I\'m using the regex

System.Text.RegularExpressions.Regex.Replace(stringToSplit, \"([A-Z])\", \" $1\").Trim()

to split strings by capital l

Answer 1

My version that also handles simple arithmetic expressions:

private string InjectSpaces(string s)
{
    var patterns = new string[] {
        @"(?<=[^A-Z,&])[A-Z]",          // match capital preceded by any non-capital except ampersand
        @"(?<=[A-Z])[A-Z](?=[a-z])",    // match capital preceded by capital and followed by lowercase letter
        @"[\+\-\*\/\=]",                // match arithmetic operators
        @"(?<=[\+\-\*\/\=])[0-9,\(]"    // match 0-9 or open paren preceded by arithmetic operator
    };
    var pattern = $"({string.Join("|", patterns)})";
    return Regex.Replace(s, pattern, " $1");
}

Answer 2

Note: I didn't read the question good enough, USAToday will return "Today"; so this anwser isn't the right one.

    public static List<string> SplitOnCamelCase(string text)
    {
        List<string> list = new List<string> ();
        Regex regex = new Regex(@"(\p{Lu}\p{Ll}+)");
        foreach (Match match in regex.Matches(text))
        {
            list.Add (match.Value);
        }
        return list;
    }

This will match "WakeOnBoot" as "Wake On Boot" and doesn't return anything on NMI or TLA

Answer 3

any uppercase character that is not followed by an uppercase character:

Replace(string, "([A-Z])(?![A-Z])", " $1")

Edit:

I just noticed that you're using this for enumerations. I really do not encourage using string representations of enumerations like this, and the problems at hand is a good reason why. Have a look at this instead: http://www.refactoring.com/catalog/replaceTypeCodeWithClass.html

Answer 4

((?<=[a-z])[A-Z]|[A-Z](?=[a-z]))

or its Unicode-aware cousin

((?<=\p{Ll})\p{Lu}|\p{Lu}(?=\p{Ll}))

when replaced globally with

" $1"

handles

TodayILiveInTheUSAWithSimon
USAToday
IAmSOOOBored

yielding

 Today I Live In The USA With Simon
USA Today
I Am SOOO Bored

In a second step you'd have to trim the string.

Answer 5

You might think about changing the enumerations; MS coding guidelines suggest Pascal casing acronyms as though they were words; XmlDocument, HtmlWriter, etc. Two-letter acryonyms don't follow this rule, though; System.IO.

So you should be using UsaToday, and your problem will disappear.

Answer 6

I hope this will help you regarding splitting a string by its capital letters and much more. You can try using Humanizer, which is a free nuget package. This will save you for more trouble with letters, sentences, numbers, quantities and much more in many languages. Check out this at: https://www.nuget.org/packages/Humanizer/