dllexport is not recognize in x64 bit platform

extern "C" _declspec(dllexport)void Export3DS(const char* inputname,const char* Objname,const char* mtlname);

I am using vs2008 C++ I开发者_开发技巧 need the dll to be output in two mode 32 bit and 64 bit. I am able to compile the code without any error for 32 bit platform but when I switch the platform to x64 bit the error C2065: 'dllexport': undeclared identifier and C2448"_declspec': function-style intializer appears to be a function definition come out. In fact when I switch to x64 platform I didn't make any changes on the code (even a single line of code). Can somebody help me? Thanks in Advance!!!

Try __declspec, with two underscores.