String Math Algebra for greater than 2^31_2^63 numbers

Question

This is a 2 Part Question...(C/C++)

FIRST PART

The Idea: I'm looking for a library that can do algebra on strings, practically can some, subtract, multiply, etc etc any virtual number, of any precision(only limited by memory).

The "maybe" solution: I keep searching on web and everyone says to use the The GNU Multiple Precision Arithmetic Library (at gmpi.org) wich is a unix based library(so they say) but is capable of working on windows(The SO i'm using, so they say).

GMP's main target platforms are Unix-type systems, such as GNU/Linux, Solaris, HP-UX, Mac OS X/Darwin, BSD, AIX, etc. It also is known to work on Windows in both 32-bit and 64-bit mode.

I started by doing some of it by myself, just to get an idea, but since i don't whant to reinvent the weel i tryed to explore the cln capabilitys on my SDK (Code::Blocks v12.11)

SECOND PART:

Starting of with some examples, i tried to make a console project with the pi.cc file... I did what they told me here but i keep getting an no such file or directory error, and changing the path or the compiler options (improvising what i shoudn't) the Program(SDK) crashes...

I did global compiler settings:

Compiler path:

C:\Users\Mr.D2\Dropbox\SourceCode Importado\Matemática\cln\include

Linker path(is that the .c files?, i think not):

C:\Users\Mr.D2\Dropbox\SourceCode Importado\Matemática

Here is a picture: here

Also i would like to ask,

Knowing that #include <...> indicates that the path is specified in the compiler, and #include "..." its a project file

What does it mean the

[EDIT]

    "#include <cln/real.h>"

mainly the cln/ notation?

I think that is all