Is there any way that you can read/process those characters that programs like 'notepad' just replace with a black box? Is there anyway to produce these? I wouldn't imagine that this would be a difficult task, even though I havn't been able to find any information on it...
Those black boxes are just characters that are not defined in the font-file, so dig up some characterers that aren't in the specific font file you're using and you'll get a blox or something similar...
Those boxes are binary data that the character set can't identify, so a graphical placeholder is used. The problem with reading that data is that it could be any data type and you don't know which. So if you input binary data with fread as an integer but the data was actually a double then you'll either get incorrect or imprecise results.