Need a method prototype

[EntryTeam]

class source code

I'm having trouble understanding line 50 - System.Convert. ToString(s, 16).
According to source code, 1st argument is char and second is radix.

I couldn't find method description and I'm wondering what exactly method does to character and what method returns?

P.S. I can only guess that method returns string, although I'm not sure.

[tlhintoq]

foreach (char s in value)
            {
                if (_Ascii7BitSigns.LastIndexOf(s) > -1)
                    sb.Append(s);
                else
                {

                    string qp = string.Format("{0}{1}",
                        _equalsSign,
                        System.Convert.ToString(s, 16)).Replace(_equalsSign, replaceEqualSign);
                    sb.Append(qp);
                }
            }

First, you need to recognize that line 50 is only part of a single line of code, that has been placed on three lines separated at the parameters to make it more human readable.

string qp = string.Format("{0}{1}",
                        _equalsSign,
                        [B]System.Convert.ToString(s, 16))[/B].Replace(_equalsSign, replaceEqualSign);

I couldn't find method description and I'm wondering what exactly method does to character and what method returns?

It does very much what it implies... It takes the char and returns a string.

The MSDN for this specific use