String format and hex chars

Question

can someone explain why this doesnt work:

string f = string.Format("\\x{0:00}{{0}}", 5);
string o = string.Format(f, "INSERT TEXT");
System.Diagnostics.Debug.WriteLine(f + " : " + o);

Output is:

\x05{0} : \x05INSERT TEXT

why does the \x05 not get replaced?

Answer 1

The format for the argument should be set in the format specifier, otherwise you're just inserting a literal "\x". Like this:

// "5" as a lowercase 2-digit hex
string f = string.Format("{0:x2}{{0}}", 5);

Don't confuse how you represent a hex literal in source code with what you would print in a formatted string, they are different things.

Answer 2

To put a literal char in a string, just make sure that the compiler knows it's a char.

string f = string.Format("{0}", (char)5);
string g = string.Format("{0}", Convert.ToChar(5));
string h = string.Format("{0}", char.ConvertFromUtf32(5));

or you can start out with a real char:

string i = string.Format("{0}", '\x05');
string j = string.Format("{0}", '\u0005');
string k = string.Format("{0}", '\U00000005');

Take your pick.