C++ Visual Studio: linking using pragma comment

Question

I came across a piece of code which uses #pragma comment(lib, "libraryname").

Why this type of usage as opposed to just linking the library from the properties menu? In what situations is this usage called for? I am in windows using C++ Visual Studio 2010.

It would be nice to see an example which calls for this type of usage.

score 33 · Accepted Answer · edited Mar 10 '15 at 12:42

33

The library writer can place a #pragma comment(lib, ...) command in the public header (.h) file. In this case, the client doesn't need to add this library to the linker dependencies list. By including an h-file in the program, the client is automatically linked to the required library.

edited Mar 10 '15 at 12:42

Peter Mortensen

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answered Oct 10 '12 at 14:12

Alex F

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do i need to also physically add the library to the visusal sutudio project in this case ? – user1612986 Oct 10 '12 at 14:23
5

No. but the library must be in the available library search path – WhozCraig Oct 10 '12 at 14:38

score 24 · Answer 2 · answered Oct 10 '12 at 14:10

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Classic example - linking against different versions of the library:

#if CURRENT_VERSION >= 10
     #pragma comment(lib, "thirdPartyLibV2.0.lib")
#else //version < 10
     #pragma comment(lib, "thirdPartyLibV1.0.lib")
#endif

answered Oct 10 '12 at 14:10

Luchian Grigore

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score 6 · Answer 3 · answered Oct 10 '12 at 14:12

It's contained in the sense that all it takes is including the header file for the associated library to be automatically pulled in. You can even do #ifdef..#endif magic to conditionally bring in the right library based on your environment.

Not everyone is going to be using your MSVC project when starting a new project from scratch, simply being able to #include and have it work is the sign of a well written library.

C++ Visual Studio: linking using pragma comment

3 Answers3

Linked