LINQ way of transforming "TheQuickBrownFox" into "The quick brown fox"

Question

Hi all,

I am trying to transform a string made of words starting with an uppercase letter. I want to separate each word with a space and keep only the first uppercase letter. All other letters should be lowercase.

For example, "TheQuickBrownFox" would become "The quick brown fox".

Obviously, I could use a simple foreach and build a string by checking each character, but I am trying to do it using LINQ.

Would you know how to solve this elegantly using LINQ?

Thank you for your help.

Answer 1

This will not be ideal for such situations as "PaulTookTheSAT" or "McDonald'sIsNasty".

string input = "TheQuickBrownFox";
string output  = input.Select((c, i) => i == 0 ? c.ToString() : char.IsUpper(c) ? " " + c.ToString().ToLower() : c.ToString()).Aggregate((a,b) => a + b);

Edit: Using (mostly) query expression syntax

string output = (from item in input.Select((c,i) => new { c, i })
                let x = item.i == 0 
                            ? item.c.ToString() 
                            : (char.IsUpper(item.c) ? " " + item.c.ToString().ToLower() : item.c.ToString())
                select x).Aggregate((a, b) => a + b);

Answer 2

You can split the words using a regular expression (and little LINQ):

public string SplitAsWords(string original)
{
    var matches = Regex.Matches(original, "[A-Z][a-z]*").Cast<Match>();
    var str = string.Join(" ", matches.Select(match => match.Value));
    str = str[0] + str.Substring(1).ToLower();
    return str;
}

A usage example:

[Test]
public void Example()
{
    string str = SplitAsWords("TheQuickBrownFox");
    Assert.That(str, Is.EqualTo("The quick brown fox"));
}

An alternative implementation using regular expression can be (with no LINQ):

public string SplitAsWords(string original)
{
    var str = Regex.Replace(original, "[a-z][A-Z]", 
        new MatchEvaluator(match => match.Value.ToLower().Insert(1, " ")));

    return str;
}

Answer 3

string s = "TheQuickBrownFox";
string transformed = s.Aggregate(new StringBuilder(), (sb, c) =>
    Char.IsUpper(c) && sb.Length > 0 ? sb.AppendFormat(" {0}", Char.ToLower(c)) : sb.Append(c)).ToString();

Answer 4

With System.Text.RegularExpressions.Regexp

System.Text.RegularExpressions.Regex.Split("TheQuickBrownFox","([A-Z][^A-Z]+)").Where(s=>s!="");

Answer 5

How about this ?

        string phrase = "TheQuickBrownFox";

        var invalidChars = from ch in phrase
                           where char.IsUpper(ch)
                           select ch;

        foreach (char ch in invalidChars)
        {
            int index = phrase.IndexOf(ch);

            phrase = phrase.Remove(index, 1);
            phrase = phrase.Insert(index, " " + ch);
        }

        Console.WriteLine(phrase);
        Console.ReadLine();