Adding space between a string (eg. HelloWord -> Hello World)

Question

Let say I've a few string: CustomerName, CustomerID, ContactNumber,...How can I transform those string to Customer Name, Customer ID, Contact Number? Is there any built-in method can be used to achieve that in c#? Or should I do it one by one manually?

Answer 1

There's no built-in method for what you are trying to achieve other than a regex based one (see solution 2).

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Solution 1 (no regex, custom method):

static string SeparateTitleCases(this string source, string separator = " ")
{
    var result = new StringBuilder();
    char previousChar = default(char);

    for (int i = 0; i < source.Length; i++)
    {
        char currentChar = source[i];

        if (char.IsLower(previousChar) && // Previous char is lowercase
            char.IsUpper(currentChar)) // Current char is uppercase
        {
            result.Append(separator); // Append separator
        }
        result.Append(currentChar);

        previousChar = currentChar;
    }

    return result.ToString();
}

Sample usage:

Console.WriteLine("CustomerName".SeparateTitleCases()); // Customer Name
Console.WriteLine("CustomerID".SeparateTitleCases()); // Customer ID
Console.WriteLine("CustomerName CustomerID".SeparateTitleCases()); // Customer Name Customer ID

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Solution 2 (regex):

string pattern = @"([^\s])([A-Z]+[a-z]*)";
string replacement = "$1 $2";            

Console.WriteLine(Regex.Replace("CustomerName", pattern, replacement)); // Customer Name
Console.WriteLine(Regex.Replace("CustomerID", pattern, replacement)); // Customer ID
Console.WriteLine(Regex.Replace("CustomerName CustomerID", pattern, replacement)); // Customer Name Customer ID

Answer 2

You could use this extension method:

private static readonly HashSet<UnicodeCategory> SeparatorCharCategories = new HashSet<UnicodeCategory>{ UnicodeCategory.UppercaseLetter, UnicodeCategory.TitlecaseLetter, UnicodeCategory.DecimalDigitNumber };

public static String SeparateCharCategories(this string input, string delimiter = " ")
{
    StringBuilder sb = new StringBuilder(input.Length);
    UnicodeCategory lastCharCategory = Char.GetUnicodeCategory(input[0]);
    for(int i = 0; i < input.Length; i++)
    {
        UnicodeCategory charCategory = Char.GetUnicodeCategory(input[i]);
        if (lastCharCategory != charCategory && SeparatorCharCategories.Contains(charCategory))
            sb.Append(delimiter);
        sb.Append(input[i]);
        lastCharCategory = charCategory;
    }
    return sb.ToString();
}

Your samples and other edge cases:

var items = new[] { "CustomerName", "CustomerID", "ContactNumber", "PurchaseOrders", "purchaseOrders", "The2Unlimited", "Unlimited2", "222Unlimited", "The222Unlimited", "Unlimited222", "ATeam", "TheATeam", "TeamA", "HTMLGuide", "TheHTMLGuide", "TheGuideToHTML", "HTMLGuide5", "TheHTML5Guide", "TheGuideToHTML5", "TheUKAllStars", "AllStarsUK", "UKAllStars" };
foreach (string str in items)
    Console.WriteLine(str.SeparateCharCategories(" "));

You see that acronyms are not supported, so HTMLGuide remains HTMLGuide:

Customer Name
Customer ID
Contact Number
Purchase Orders
purchase Orders
The 2 Unlimited
Unlimited 2
222 Unlimited
The 222 Unlimited
Unlimited 222
ATeam
The ATeam
Team A
HTMLGuide
The HTMLGuide
The Guide To HTML
HTMLGuide 5
The HTML 5 Guide
The Guide To HTML 5
The UKAll Stars
All Stars UK
UKAll Stars

Answer 3

I'm assuming that CustomerName, CustomerID are property names? You would need some way to reflect those names and you could then use the Humanizer Lib to add the whitespaces.

Use it like this:

"CustomerName".Humanize(LetterCasing.Title) => "Customer Name";