Is there any way to do this, assign a value within a List.ForEach() statement?

Question

I have this:

var lineArray = line.Split(\';\');

lineArray.ToList().ForEach(x =>
{
    if (x == \"(null)\")
        x = \"NULL\";
    else
        x = string.         


        

Answer 1

var lineArray = line.Split(';')
                    .Select(x=>x == "(null)"
                               ? "NULL"
                               : string.Format("'{0}'", x))
                    .ToArray();

you are trying to use List.ForEach(Action action) with lambda expression (T is string here)

if lambda expression is replaced with named method it turns out that only method argument is modified, but changes are not reflected on calling side, because x is not ref argument

private void Replace(string x)
{
    if (x == "(null)")
        x = "NULL";
    else
        x = string.Format("'{0}'", x);
}

var list = lineArray.ToList();
list.ForEach(Replace);
// check list here and make sure that there are no changes

ForEach could work if T is a reference type and action modifies some properties but not the reference itself