Just built npp 6.8.8 x64 from source...

Edward Pang

It’s surprisingly easy: start the x64 native command line from VS 2013 community edition, and following the steps in source tree(PowerEditor\visual.net) and scintilla\win32)
With x64 binary, I can now open > 1GB files. There are a couple of issues:

I have to use the NOBOOST=1 option for building the scintilla DLLs. If I use the boost library, there are 16 unresolved external symbols.
The plugins cannot be loaded, apparently because they are 32bit dlls. Probably I can build the plugins as x64 if I really need them.

Note: the right click handler:“Edit with Notepad++” may cause crash if the x64 binary is not copied to the installed location.

dail

I know a few other people have built a 64-bit version of it. It’s not without its problems as you have found out. Although even if you are able to open > 1GB files, Notepad++ is not really made to be very user friendly when handling large files.

Edward Pang

Just made the DSpellCheck plugin to work in x64. It turned out it’s more difficult than making NPP work in x64. I have to change 2 function pointers from long to LONG_PTR.