I have inherited some ancient Windows C++ code and have created a project for it in Visual Studio 2010. When I build, I get missing header file errors for system files such as "precom.h" and "Classes.hpp". They do not exist on my machine. Is anyone familiar with these files and where they come from? Thanks.
They're not standard Windows files. My guess is that whoever you inherited the code from forgot to check the files into source control.
Go find that person, and glare at them until they find them!
The name precom.h is suggestive of a precompiled header. If that's true, then it may be a matter of getting the project set up to generate the precompiled header.
Related
i just started learning c++ lately and i am using visual studio 2015. But i have to manually remove the #include stdafx.h in my cpp file before upload it to the test server for my class, or it just sends back an error like this:the error from test server
I would like to know why this issue is happening. My guess is that this thing is exclusive to windows and x86 based OS?
Any help would be appreciated. :D
You'll need to upload all your sources. stdafx.h isn't special in that regard. Of course, if your course restricts you to one .cpp upload, then you can't use stdafx.h for that course
stdafx.h is the default name of a precompiled header for a Visual Studio project. However, you can certainly have a file named this on other environments. Note that the Visual Studio compiler processes this header slightly differently than it does other headers, if it is specified as the precompiled header in your project's property pages (C/C++ -> Precompiled Headers - see here for more details). For example, multiple includes of this file with different preprocessor defines will be ignored when it is the precompiled header (which isn't that common, but something to be aware of).
If you want to make portability to non-Visual Studio environment easier, it's usually easier to disable precompiled headers in your Visual Studio project. If you continue to use the stdafx.h file in your code, you will obviously need to upload it to your test compilation server, and may need to modify it and/or its inclusion into your code.
When I go to debug my C++ project in Visual Studio, up pops a little warning dialogue box that tells me:
A copy of datum.h was found in
c:/users/brad/desktop/source/binary/datum.h, but the current
source code is different from the version built into
c:/users/brad/desktop/source/binary/datum.h.
I'm having trouble understanding what this is even trying to tell me, let alone how to fix it. At first I thought it might be complaining that I'd accidentally duplicated a file in the directory, which I checked, and found nothing of the sort, which leaves me pretty stumped. I also tried excluding the file from the solution and adding it again, which didn't fix the problem either.
The warning doesn't appear to actually hinder the development of my project, but I suppose warnings exist for a reason, so if anyone knows what's gone wrong, any advice would be greatly appreciated. To my knowledge, I didn't change anything to cause the message to appear, it just popped up one time I went to debug the solution and has kept on appearing ever since.
Also, more copies of the same warning have started popping up, pertaining to other header files in my solution (I haven't recieved any about .cpp files yet, but it could be a coincidence, because it's only been going on for about 20 minutes).
Try removing breakpoints from the file in question.
This worked for me when it occurred with Visual Studio 2013 for a header file in debug build.
Source: Release mode file sync issue - current source code different from the version built
Additional notes: Clean / Rebuild also works, but that is painful for regularly changing code. Enabling the break point after starting debugger merely delays the message.
I solved it:
Close the window of the .h file in Visual Studio if it's open.
Close Visual Studio.
CUT the .h file from its normal location and paste it into a temporary folder that VS doesn't know about.
Restart VS and compile. It'll complain about the missing .h file. Good -- Make the bastard beg for it!
Paste the .h file back into its original location.
Compile. VS will gratefully accept the missing file. (Damn I hate Microsoft!)
This occurs if you rename an implementation file (*.c, *.cpp, etc.) to a header file.
This is because the Item Type still remains as C/C++ Source File, making it get compiled as a separate translation unit rather than as an actual header, preventing Visual Studio from recognizing its inclusion as a header elsewhere.
It took me quite a while to figure this out.
To fix this:
Right-click your header file in Solution Explorer and select Properties.
Select All Configurations, All Platforms.
Under General, change Item Type to C/C++ Header.
Press OK.
Force-recompile any file that #includes your header (or just Rebuild the solution).
The problem is that the debugger thinks that the checksum of the source file is different from what the compiler calculated and put in there. The debugger will then refuse to apply breakpoints in the files that mis-match, to prevent you from seeing data it can't guarantee is correct.
I have had this keep happening even after a clean rebuild. This is with VS 2015. My guess is perhaps the debugger and the compiler disagree on how to hash newlines or something like that? The fix is to turn off "require source files to exactly match the original version" in Debug -> Options -> Debugging -> General
Could you by any chance be debugging another executable (not the one actually built?). This is a common issue in scenarios where Visual Studio builds the binaries in one directory but then they are copied over to some other directory for debugging. I'd suggest you compare the target path under the debugging settings and the output directory under the general settings in Visual Studio.
This would explain the issue, since you are actually debugging some older version of the binary (not the one built currently) and thus the warning, since Visual Studio can't find the version of the source files for that version of the binary.
The reason may be circular header dependencies. datum.h may includes another_header.h (directly or indirectly), which includes datum.h.
I see the real reason of this question is not answered. So for someone still looking, here it goes...
The most common reason of this problem is that the source files used to build the existing obj files are different than the existing ones. In other words the
particular project did not build after new modifications to source. The solution to this problem is to rebuild the project after modifying.
This happened to me in situation where I had modified my static library projects files and then without building that project I started my application project which was using this static library project.
this worked for me:
close VS
delete *.vcxproj.filters file
restart VS
problem should be gone.
this worked for me:
clean project
debug/delete all breakpoints :)
This worked for me (as of March 2019):
Click the 'Build' drop-down menu in the top left of your Visual Studio window
Select 'Rebuild Solution'
I've changed the file name and it works now.
Just encountered this. In my case, one of my .h files contained implementation (a class with static methods), which was #included by one of my .cpp files, but the Project Settings were also telling Visual Studio to compile the .h file.
I manually edited both the .vcxproj and .vcxproj.filters project files, moving the .h file from the <ClCompile> ItemGroup to the <ClInclude> ItemGroup.
This did the trick for me; I never saw the "A copy of...is different from..." pop-up again.(Note that this was after I had thoroughly failed in attempts to get <DependentUpon> to work.)
My solutiion:
Build -> Configuration manager
Switch to another configuration (any, example Releas or Debug)
Switch to previous configuration
It is possible to have multiple projects, each with their own entry point within a solution. Make sure that the correct project is being run.
The source code is different message can appear in a project A's source when you are running project B. In this case, the message can mean This breakpoint won't be hit because you're running a project that doesn't include it
I've used Visual Studio's 'Code Maps' extensively for my C# projects in the past. I'm now working on a native c++ project and running into problems. When I add a class or method to a Code Map I get the following error message with no context or help available. Any ideas what the cause is?
Error Fail to get symbol's namespace
I should not that the project compiles and runs without a problem.
This MSDN page on Code Maps notes under Requirements that C++ has limited support.
Turns out it was my mistake and not a bug. I had incorrectly put includes in my headers such that almost all .cpp files included all .h files even if they weren't needed. It appears this caused the codemap application to crash. I went through and correctly included only the required .h files and correctly created my precompiled headers. This makes the codemap run as it should.
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.
In some of my VS 2005 projects, when I change an include file some of the cpp files are not rebuilt, even though they have a simple #include line in them.
Is this a known bug, or something strange about the projects? Is there any information about how VS works out the dependencies and can I view the files for that?
btw I did try some googling but couldn't find anything about this. I probably need the right search term...
I've experienced this problem from time to time, and with other IDEs too, not just VS. It seems thatv their internal dependency tree sometimes gets out of whack with reality. In these cases, I've found deleting pre-compiled headers (this is important) and doing a complete rebuild always solves the problem. Luckily, it doesn't happen often.
To be honest I never faced such a problem using Visual Studio. Your CPP should be rebuild as well if it includes the header. The only reason I can come up with: same include file is taken from 2 different sources.
You can try do debug this at compile time, by enabling the preprocessor to output preprocessed files. Click on the CPP file go to properties and then to C/C++->Preprocessor and select in "Generate Preprocessed File" the item with or without line numbers.
Go to you include file put the pragmas around your newly added definitions like:
#pragma starting_definition_X
...
#pragma ending_definition_X
Now compile everything. There will be a newly created file with the same name as CPP but with extension .I (or .i).
Make a search if your pragmas are there. If not, your include come from another place.
If you use pre-compiled headers, you cpp should rebuild. There is also a pragma once statement in MS VC, which parses the include file only once, but that should still recompiler you cpp-file.
Hope that helps,
Ovanes
Do you have the "Minimal rebuild" option turned on?
Visual studio compares the timestamps on the files. So you might want to check that your system clock is set correctly and also that none of the files has a funny timestamp on it. Look at the include files, the cpp files, the pch files and obj files and make sure all the timestamps look reasonable. In particular, make sure none of them are in the future.
Was the .h files added in the project? If not, then vs maybe unable to find out the dependency.
Thanks for all the answers they have helped point me in the right direction.
I have discovered that deleting the idb file and rebuilding will then allow subsequent modifications of .h files to cause the correct .cpp files to be built. However this causes the entire project to be rebuilt which just brings me back to Neil Butterworth's suggestion of doing a full rebuild. I don't think there is much else I can do about it.
As an aside, looking at the bad and good idb files I can see that the cpp file that was not being built is not in the bad idb, whereas it is in the good idb. The header file that is being changed is mentioned several times in both files.
win_pdbx (download) can extract the idb file and moyix has published some information about the streams in these files.
Stream 4 contains the file paths of the cpp files but I have not been able to determine the format.