Why is it necessary to write shellcode in pure C++ without inline assembly for 64-bit environments?

Visual Studio's inline assembly (`__asm`) is not supported in 64-bit builds. To generate 64-bit shellcode, you must avoid inline assembly entirely and use pure C++ code that dynamically resolves API addresses and calls functions. This approach improves readability and debugging, and it is compatible with both x86 and x64 if you handle the differences in calling conventions (e.g., using `__fastcall` for x64). See the article for a full implementation that retrieves `GetProcAddress` and `LoadLibrary` at runtime.