Compiler switch /Platform

On drilling one of C# compiler (CSC) switch /platform, learned quite interesting info. Letz share it here.

Platform has 4 key switches, anycpu(default), x86, x64 and Itanium. anycpu switch creates PE32/agnostic signature in managed module, which runs as 32 bit app in x86 Windows, as 64 bit in x64 Windows and 64 bit in IA64 Windows. Second switch x86 creates PE32/x86 sign in module, which runs as 32 bit in x86, WoW64 (Windows on Windows64) in x64 & IA64 Windows.

x64 switch creates PE32+/x64 in managed module, which runs as 64 bit app only in x64 Windows. Last switch Itanium makes PE32+/Itanium signature, which runs as 64 bit app only in IA64 Windows.

Windows OS loads x86, x64, or IA64 version of MSCorEE.dll into the process’s address space from C:\Windows\System32 directory. For WoW64, it loads from C:\Windows\SysWow64 directory. Primary thread calls a method defined inside MSCore.dll. This method initializes the CLR, loads the EXE assembly, and then calls its entry point method (Main). At this point, the managed application is up and running.

.NET FW 4.0 has Environment’s Is64BitOperatingSystem property to determine if it is running on a 64-bit version of Windows