How to know the size of the string in bytes?

Question

You can use encoding like ASCII to get a character per byte by using the System.Text.Encoding class.

or try this

  System.Text.ASCIIEncoding.Unicode.GetByteCount(string);
  System.Text.ASCIIEncoding.ASCII.GetByteCount(string);

From MSDN:

A String object is a sequential collection of System.Char objects that represent a string.

So you can use this:

var howManyBytes = yourString.Length * sizeof(Char);

System.Text.ASCIIEncoding.Unicode.GetByteCount(yourString);

Or

System.Text.ASCIIEncoding.ASCII.GetByteCount(yourString);