I'm sure of its existence, I was reading a book about C++ and they used the same library.
That doesn't mean that it's necessarily installed on your computer. You need to verify that it is, in fact, installed.
Do you know how to do that?
I'm not familiar with Code::Blocks, but somewhere in the settings will be an option to specify the include paths.
Of course, to do that, you'll need to know which directory the file is in, which you'll find out when you verify whether the file's actually installed.
So it looks like you're going to have to download it as put it somewhere that your compiler can find it. From the comments in the header, it seems it simply does mapping between utf8mb4 and dos character sets.
Okay. I just wanted to be able to use the whole Swedish alphabet, because whenever I try to use Å, Ä or Ö it outputs some other weird sign. Maybe there is some other way to include those letters without having to write a number combination each time?