How to reference a dll to Visual Studio without lib file

The only way to access a bare DLL without a .lib file is to load the DLL explicitly with LoadLibrary(), get pointers to the exported functions you want to access with GetProcAddress(), and then cast those pointers to the proper function signature. If the library exports C++ functions, the names you have to pass to GetProcAddress() will be mangled. You can list the exported names with dumpbin /exports your.dll.

extern "C" {
    typedef int (*the_func_ptr)( int param1, float param2 );
}

int main()
{
    auto hdl = LoadLibraryA( "SomeLibrary.dll" );
    if (hdl)
    {
        auto the_func = reinterpret_cast< the_func_ptr >( GetProcAddress( hdl, "the_func" ) );
        if (the_func)
            printf( "%d\n", the_func( 17, 43.7f ) );
        else
            printf( "no function\n" );

        FreeLibrary( hdl );
    }
    else
        printf( "no library\n" );

    return 0;
}

As has been noted by others, a LIB file can be created. Get the list of exported functions from dumpbin /exports your.dll:

ordinal hint RVA      name
      1    0 00001000 adler32
      2    1 00001350 adler32_combine
      3    2 00001510 compress
(etc.)

Put the names into a DEF file:

EXPORTS
adler32
adler32_combine
compress
(etc.)

Now make the LIB file:

lib /def:your.def /OUT:your.lib

For cases where the name has been decorated, either by C++ name mangling or 32-bit stdcall calling convention, simply copy and paste whatever names dumpbin reported, mangling and all.

If you don't have a .lib file you can create one from the .dll:

https://web.archive.org/web/20160228170508/https://adrianhenke.wordpress.com/2008/12/05/create-lib-file-from-dll/