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Editorial Team
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Asked: 2026-06-18T16:52:19+00:00

My objective is to create a dll and lib file so i’m following this

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My objective is to create a dll and lib file so i’m following this guide
1) I created a new win32 Console Application project in VS, chose DLL as ‘Application Type’ and Emptied Project
2) I’m trying to create a database in C++. So I have 5 headers with ONLY function declarations.
3) Database.h is my top header, it looks like this:

#ifdef DBDLL_EXPORTS
#define DBDLL_API __declspec(dllexport) 
#else
#define DBDLL_API __declspec(dllimport) 
#endif
#ifndef __Database_H
#define __Database_H


#include "Table.h"

class DBDLL_API Database { ... };
#endif

4) Now with only headers, I tried compiling the project. It compiled but I don’t see any DLLs or Libs anywhere in the project folder. How do I create them?

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1 Answer

  1. Editorial Team

    This is because headers are not compiled — only CPP files are compiled (which pull in the headers — a source file and all the headers it pulls in is called a “translation unit”, which is the thing actually being compiled (independent of other TUs)).

    So, in effect, the build system thinks you’re building an empty project, and in this case generates nothing at all. Note that even if the headers are pulled in and compiled, unless an exported symbol is actually referenced somewhere, it may be optimized out. In such cases, you will get an (empty) DLL, but no .lib file (which can cause errors down the line if you have dependent projects looking for this .lib before there’s anything in the DLL).

    You’ll need to create some CPP files that implement the functions declared in the headers. If you have everything in the headers and don’t need any CPP files at all, then there’s no point in having a DLL! (Since you could include the headers in any other project without needing any other dependency.)

    Finally, your include guard (#ifndef ...) should encompass the entire header, including the DLL export macros, otherwise you’ll eventually get macro redefinition warnings.

    I would suggest using #pragma once instead of include guards since it’s simpler and recognized by pretty much every compiler. I would also put the DLL macro goop into its own header (e.g. “dllmacros.h”) and include that where it’s needed (this will reduce duplication).

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