c# - Changing element value in List<T>.ForEach ForEach method

Question

I have the following code:

newsplit.ToList().ForEach(x => x = "WW");

I would expect that all elements in the list are now "WW" but they are still the original value. How come? What do I have to do different?

Answer 1

Assuming that newsplit is an IEnumerable<string>, you want:

newsplit = newsplit.Select(x => "WW");

The code that you currently have is equivalent to the following:

foreach(string x in newsplit.ToList()) {
    AssignmentAction(x);
}

...

public static void AssignmentAction(string x) {
    x = "WW";
}

This method won't modify x because of the pass-by-value semantics of C# and the immutability of strings.