c# Lambda, LINQ .... improve this method

Question

I am in the process of learning more about LINQ and Lambda expressions but at this stage, I simply don't "Get" Lambda expressions.

Yes ... I am a newbie to these new concepts.

I mean, every example I see illustrates how to add or subtract to parameters.

What about something a little more complex?

To help me gain a better understanding I have posted a small challenge for anyone who wishes to participate. I have the following method which will take any string and will put spaces in between any upper case characters and their preceding neighbour (as shown below).

i.e.
"SampleText" = "Sample Text"
"DoesNotMatterHowManyWords" = "Does Not Matter How Many Words"

Here is the code;

public static string ProperSpace(string text)
{
    var sb = new StringBuilder();
    var lowered = text.ToLower();

    for (var i = 0; i < text.Length; i++)
    {
        var a = text.Substring(i, 1);
        var b = lowered.Substring(i, 1);
        if (a != b) sb.Append(" ");
        sb.Append(a);
    }

    return sb.ToString().Trim();
}

I am sure that the method above can be re-written to use with LINQ or a Lambda expression. I am hoping that this exercise will help open my eyes to these new concepts.

Also, if you have any good links to LINQ or Lambda tutorials, please provide.

---

EDIT

Thanks to everyone who has contributed. Although the current method does do the job, I am happy to see it can be modified to utilize a lambda expression. I also acknowledge that this is perhaps not the best example for LINQ.

Here is the newly updated method using a Lambda expression (tested to work);

public static string ProperSpace(string text)
{
    return text.Aggregate(new StringBuilder(), (sb, c) =>
    {
        if (Char.IsUpper(c)) sb.Append(" ");
        sb.Append(c);
        return sb;
    }).ToString().Trim();
}

I also appreciate the many links to other (similar) topics.

In particular this topic which is so true.

Answer 1

This is doing the same as the original code and even avoids the generation of the second (lower case) string.

var result = text.Aggregate(new StringBuilder(), 
    (sb, c) => (Char.IsUpper(c) ? sb.Append(' ') : sb).Append(c));