Can't create simple DLL example

Question

I followed microsoft documentation and stumbled at moment when DLL project should compile like this:

1>------ Build started: Project: MathLibrary, Configuration: Debug Win32 ------  
1>  stdafx.cpp  
1>  dllmain.cpp  
1>  MathLibrary.cpp  
1>     Creating library c:\users\username\documents\visual studio 2015\Projects\MathLibraryAndClient\Debug\MathLibrary.lib and object c:\users\username\documents\visual studio 2015\Projects\MathLibraryAndClient\Debug\MathLibrary.exp  
1>  MathLibrary.vcxproj -> c:\users\username\documents\visual studio 2015\Projects\MathLibraryAndClient\Debug\MathLibrary.dll  
========== Build: 1 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========  

But i compiling my DLL project successfully but i have less in output. And in a result my main app can't compile because "there is no .lib file of your DLL" as compiler said.

Output of DLL project looks like this:

1>------ Rebuild All started: Project: testDLL, Configuration: Debug Win32 ------
1>stdafx.cpp
1>dllmain.cpp
1>someClass.cpp
1>testDLL.cpp
1>Generating Code...
1>testDLL.vcxproj -> D:\stud\VStest\testDLL\Debug\testDLL.dll
========== Rebuild All: 1 succeeded, 0 failed, 0 skipped ==========

My output obviously lacks "Creating library" part. I don't understand what's wrong, my VS is 2017.

P.S. what MS mean by that comment in CPP file?

// Compile by using: cl /EHsc /DMATHLIBRARY_EXPORTS /LD MathLibrary.cpp 

Answer 1

In your DLL project goto

Project Settings -> C/C++ -> Preprocessor -> Preprocessor definitions

And add

MATHLIBRARY_EXPORTS definition

So MATHLIBRARY_API macros

#ifdef MATHLIBRARY_EXPORTS  
#define MATHLIBRARY_API __declspec(dllexport)   
#else  
#define MATHLIBRARY_API __declspec(dllimport)   
#endif  

will be solved to __declspec(dllexport). This will instruct compiler/linker to export function marked with this attribute into DLL export section as well as into import library (if you have the project setting to create import library ).

As well as, you can implement your class as following:

namespace MathLibrary  
{  
    // This class is exported from the MathLibrary.dll  
    class MATHLIBRARY_API Functions  
    {  
    public:  
        // Returns a + b  
        static double Add(double a, double b);  

        // Returns a * b  
        static double Multiply(double a, double b);  

        // Returns a + (a * b)  
        static double AddMultiply(double a, double b);  
    };  
}  

Alternatively you can use def files instead of __declspec