There are a lot of questions concerning the problem of being unable to create the 64-bit configuration of a project in Visual Studio, or, compile an existing 64-bit project. Almost always, this problem arises from the absence of the 64-bit compiler. There are two reasons why the 64-bit compiler is missing:
- You are using the Visual Studio Express version, which lacks the 64-bit compiler. In this case you should get a corresponding edition of Visual Studio.
- The option of installing the 64-bit compiler was disabled by default when installing Visual Studio 2005/2008 (Figure 1). It is most likely that you have not enabled the "X64 Compilers and Tools" check box during installation. If so, launch the installer and install the missing items.
Figure 1 - The 64-bit compiler is disabled before the installation