ProudNet offers the string classes called Proud.String and Proud.StringA.

The string class allows you easily handle the string such as ATL or STL. For instance,

Proud::String a;  // Empty string
a = L"123";         // Adding values in string.
puts(a);            // a itself provides the string buffer directly.
a += L"abc";        // Adding another string to the string.
if(a == L"123abc")  // Way to compare the contents in the string.
{
a.Replace(L"123", "def");   // Replacing the contents of string
}

Most of ProudNet APIs use Proud.String while some specific APIs use Proud.StringA.

Reference