I probably misunderstand how the compilers work,but I have the following situation.I have a VC++ 2012 project.The project contains an API with hundreds of classes.Now, I create 'main' entry point file where I just use some std stuff.The main doesn't include even a single header from the API.Yet when I compile I see that pretty everything from the API is getting compiled into the executable?Why does it happen?Is it something I should configure in the project properties?
Source files that are part of the project are compiled also if "unused" through headers and references from your main routine.
If you don't want those compiled simply remove them from the project. The compiler might be able to optimize everything away but that doesn't mean they're not compiled if part of the project first.
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Let say we have a large code base and we are doing development in C++. Do we have to recompile everytime in order to test the code?
If yes then it is going to take ages to do development.
What's the solution to this problem?
Yes, you'll definitely need to compile C++ code if you want to test it. C++ code can't be executed without being compiled.
However, if you organize your project smartly, compilation could take only a few seconds, or maybe up to a minute, even if there are thousand (or even more) of files.
By default, your build system will run an incremental build, except if you explicitly request a "rebuild" or did a "clean" previously. It will then invoke the compiler/linker accordingly and make sure it compiles/links only what needs to be (if a cpp file did not change, no need to compile it, this is all based on file timestamps, if the "object" file (generated) is older than the cpp file (source), the build system knows it's up-to-date and won't generate it again. If you use Visual Studio and/or CMake or whatever IDE, build system, they all support that!
Additionally, you can follow some guidelines to make this even faster:
Firstly, organize your project in modules (libraries), ideally with dynamic link. Then when a file from a library is changed, only this library needs to be compiled (other libraries or programs using the modified library won't have to be compiled again).
When you'll modify only an implementation file (cpp file), only this file + link of the module using it will be needed.
When you'll modify an header file (h file), all cpp files including it will need to be recompiled, so you must be careful to optimize your includes. Prefer forward declaration (see why here)to includes whenever it's possible (else, your header becomes a dependency of all cpp files using the other header file including yours...as a cascade, modifying this header file will end up requiring compilation of tones of cpp files). Don't include files you don't need (because it will fire a new useless build when the header file changes). Possibly use precompiled headers to speedup compilation.
Note: As commented, there are apparently some tools that can interpret C++ without compiling it...but that's not what C++ was designed for at the first time. And I doubt they will be fast as compiled code at runtime....so you'll probably save 20sec of incremental build time and then loose minutes at runtime....
I want to ask something that might sound stupid but I dont know how to get over it.
I wrote a C++ program with some header files and 2 cpp files, one of which includes main.In the header files there are the definitions of some classes I created that have some inline functions and some functions that I declared in the classes and defined in one of the cpp files (not the one with main).
The program compiled and run fine but I wanted to change a few details in some of the inline functions of the classes. I did those changes and the program compiled and ran BUT it was using the previous version of the header files and not the new one.
I have tried creating a new project using the new files but even then the program will actually use their old version.
I am using Dec-C++5.11 in windows 10.
Solved. Looks like I needed to change the file name. Thank you very much!!
Some build systems will only perform "incremental" builds, so if you change a source file then that source file is recompiled, but unless you rebuild the whole project your original header content may still be used. This is even more so the case if you are using precompiled headers, and it may also affect inline functions in that their content has already been "inlined" into source files for whom a rebuild is not being triggered.
Changing the header's filename will work around this "cache" in many cases, but the correct (and far more user-friendly) approach is to ensure that you instruct your IDE to rebuild the entire project from scratch. In Dev-C++, that option is called "Rebuild All". I would generally recommend this option whenever you alter a header file.
(If you were using GNU Makefiles, you would perform make clean before your next make all).
I have a embedded controller code handed over, it has a bunch on .c files and some headers and a lot of associated files for the embedded processor, its a motorola MC9S12DT256 and it uses a not-so-good compiler - Cosmic. i used Visual studio(just a txt editor) for modifying the code and it changes the hex file being burned to the processor.
I got it earlier this week and spent most of my time on it and it worked ok for minor changes (where changin a value in the code and compiling again made the necessary changes) Now i have to make some major changes. The code calls certain functions which are not to be found any where in the all of the .hpp/.h/.cpp i got. there are no associated dlls as well. I tried to find some basic link and put it in a .sln and still most data is not recognized (as in i cant go to declaration of defn).
So my question is - how to get to the function definiton to where it is called when VS blanks out. Find all references also does no help
Thanks
PM
They may be compiler intrinsics (functions provided by the compiler rather then in a library). But it is not clear how you have determined that they do not exist in a static library or why you think you should be able to see a definition (as opposed to a declaration).
When using Visual Studio as an embedded project IDE, you should create the project as a "makefile project" (even if you don't actually have a makefile), and you need to add all the necessary header paths for your embedded code and the Cosmic compiler standard header folder as include files to the project - VS scans the header files for declarations for Intellisense code completion and browser navigation.
Greetings fellow programmers! I am trying to create a C++ library to use in other projects. This library is to be a static library that will be linked to other projects.
Problem: The compiler doesn't seem to catch errors that it otherwise would if it were configured as an executable program under Project->Properties>General. In fact I purposely made a syntax error and the compiler
gave me a success regardless.
Is there a way to force the compiler to check everything while building a static lib?
Build Environment: Visual Studio 2010
EDIT: As it turns out, it was a rather simple, yet incredibly subtle mistake. It turns out that Visual studio was treating some of my .cpp files as header files. Because of this, the compiler was not running through the code at all (no one includes .cpp files). When adding files to the library, I must have accidentally selected header instead of C++ file. I thought Visual Studio would only rename the header file. I guess I was wrong!
This is nonsensical. It cannot happen. What is probably happening is that you think that the compiler is compiling your source file, (the one with the syntax error,) but it does not. Perhaps you have not added your source file to your project.
(Then again, C++ has a pretty quirky syntax; I hope you are sure that what you made was in fact a syntax error, and not a syntactically valid language construct.)
If you have more than one project in the workspace (solution) like exe and lib, make sure you click on the exact one to build or set it as the startup project (showing up in bold letters) if you hit the F7 button.
I'm a beginner starting to use Microsoft Visual C++ Express 2010 for Windows Programming. I've created a new C++ application using native code, not managed or MFC. I had Visual Studio create for me the basic windows code to create one window with simple menus (chat.cpp). I modified this file and I was able to compile correctly and see my changes take effect.
Now I've added one more source file to the solution (intro.cpp) which I include in my header and call from within chat.cpp. This seems to work just fine, but with one problem. The compiler doesn't seem to be applying my code changes occasionally: I make various edits, recompile, and the "old" code seems to be running. Then, after a while, after I make only a tiny modification, the compiler seems to "catch up" and it runs the new code including all the previous changes I had made.
Is there some kind of cache? Do I need to tell the compiler which files to compile and which ones to just link from object files? Did I make a mistake when I added the file to the solution?
Does intro.cpp have a header file? is that in your solution too?
It's hard for me to imagine that this area of such a mature IDE has a bug here, so I would examine your file list first. Make sure that the Solution Explorer shows all the files you have added and are editing. This is the list that VS uses to determine rebuild is needed.
EDIT: I admit it's not clear to me from your description why it would fail right now. However, typically header files do not include code, it works the other way around (except for class template header files, such as the STL headers). There is some discussion about pros and cons here. The most compelling argument to me in favour of code including headers rather than vice versa is that the header file contains the interface, while the code file contains the implementation.
I would try restructuring your code to a more traditional structure where intro.cpp includes intro.h and any others it needs, and the same with chat.cpp. Then your compilation units are intro.cpp and chat.cpp, and they depend on the associated header files, so provided they are properly listed in the SOlution Explorer, all should work. You can clean up the build dependencies to avoid dups and reduce build time once you have it working as you wish.