Question

I have a textbox with multiline enabled, and want to add a string at the beginning and end of
each line, so every line would be changed to

a + line + b

Now I know it has to do with a foreach loop, but don’t know how to write it out.

Answer 1

Well, the Lines property is probably the one you want. Three options:

string[] lines = textBox.Lines;
for (int i = 0; i < lines.Length; i++)
{
     lines[i] = a + lines[i] + b;
}
textBox.Lines = lines;

Or:

textBox.Lines = Array.ConvertAll(textBox.Lines, line => a + line + b);

Or:

textBox.Lines = textBox.Lines
                       .Select(line => a + line + b)
                       .ToArray();