How to share data between different instance of same DLL

Usually Dlls are loaded into its corresponding process address space. Indeed the code is shared between all instances but not the global data. So the issue that we might face is – how can we share common data between all dll instances?

#pragma data_seg (".MYSEG")
    int g_nInteger = 0;
    char g_szString[] = "hello world";
#pragma data_seg()

// Tell the linker that the section
// .MYSEG is readable, writable and is shared.
#pragma comment(linker, "/SECTION:.MYSEG,RWS")

Here we are declaring our data segment and are telling that, this segment is RWS – readable, writable and shared. This way we manage to share this data segment between all dll instances.