im starting to learn C++ (just finished with C) and Im trying to use strings. Ive included the library, and i get this error when compiling:
Severity Code Description Project File Line Suppression State
Error C4996 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS.
Now I know that this is due to the risk in buffer overflow, but in my task I have to do it that way.
I've read that adding the #define _CRT_SECURE_NO_WARNINGS is suppose to remove that warning, but it doesnt...
In your project setting, C/C++ -> Command Line, add following:
/D_CRT_SECURE_NO_WARNINGS
This will remove the warning.
Use _CRT_SECURE_NO_WARNINGS in C/C++ -> Preprocessor -> Preprcessor Definitions.
Related
I have simple console application in which I must set preprocessor definition _CRT_SECURE_NO_WARNINGS. According to my understanding I can set it my code right after #include "stdafx.h" by puting line #define _CRT_SECURE_NO_WARNINGS or in Project Properties -> Preprocessor -> Preprocessor Definitions. If I do first way I still have problems in code if I do second way - it solves my problem. Why I can't define #define _CRT_SECURE_NO_WARNINGS in source code?
The best way to solve this problem is really on the project properties, causing it to be used globally as a compiler flag. If you use the #define _CRT_SECURE_NO_WARNINGS in a file, only that file will have that warning suppressed.
I'm trying to write a plugin for 3ds max, I went through the entire sdk installation process to the letter as described in the help files.
The problem I'm facing though is intellisence complaining about an invalid macro definition
"IntelliSense: command-line error: invalid macro definition:_CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES_COUNT =1"
I found the definition in project settigs -> c/c++ -> preprocessor definitions as inherited from parent or project default.
I tried disabling the inherited definitions and re-entered them, this time without the space between the name and the = and all works fine so I'm guessing its a typo on their part?
Anyway, I want to change the default project or whatever to not repeat it every time i start a new project. The project is created with a wizard which required me to copy over some files to appear and after which I had to enter the sdk path.
The files I copied are plain text with some fancy extensions and not much in them so I'm guessing the defaults are described in the sdk directory.. somewhere. Does anybody know what kind of a file I'm looking for?
EDIT: I found a file called root.vcxproj_template and it has a section for preprocessor definitions but all it contains is
<PreprocessorDefinitions>_USRDLL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
and no mention of the broken one
EDIT2: in another part of the file there was a path to a property sheet (maxsdk\ProjectSettings\propertySheets\3dsmax.common.tools.settings) which included the faulty definition. I fixed it an no more complaints from VS.
_CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES_COUNT = 1 means that compiler should replace all old C run-time routines such as sprintf, strcpy, strtok with new versions such as strprintf_s, strcpy_s, strtok_s and similar. It goes in pair with following definition _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES = 1.
More you can find here: (MSDN) https://msdn.microsoft.com/en-us/library/ms175759.aspx. However I tried to use this but without success. It says that you can use this only for statically allocated buffers like char buffer[32], but compilers was still complaining bout unsecure strcpy.
I'm using bison & flex (downloaded via cygwin) with vc++. When I compile the program I got an error:
...: fatal error C1083: Cannot open include file: 'unistd.h': No such file or directory
The corresponding code in the flex-generated file is:
#ifndef YY_NO_UNISTD_H
/* Special case for "unistd.h", since it is non-ANSI. We include it way
* down here because we want the user's section 1 to have been scanned first.
* The user has a chance to override it with an option.
*/
/* %if-c-only */
#include <unistd.h>
/* %endif */
/* %if-c++-only */
/* %endif */
#endif
If I define YY_NO_UNISTD_H in the flex file(.l) this error will disappear, but I get several other errors:
...: error C2447: '{' : missing function header (old-style formal list?)
...: warning C4018: '<' : signed/unsigned mismatch
...: error C3861: 'isatty': identifier not found
How can I fix this problem?
All these errors occur in the flex-generated scanner.
I know it's because unistd.h doesn't exist in windows. Do I have to write my own unistd.h? If so how to write it in order to eliminate those errors?
isatty is used by the lexer to determine if the input stream is a terminal or a pipe/file. The lexer uses this information to change its caching behavior (the lexer reads large chunks of the input when it is not a terminal). If you know that your program will never be used in an interactive kind, you can add %option never-interactive to you lexer. When the program is run with user input, use %option interactive. When both uses are desired, you can either generate an interactive lexer, which gives a performance loss when used in batch mode, or provide your own isatty function.
Use %option nounistd in your .l file to remove the dependence on unistd.h.
just in case somebody's still this problem, Flex comes with unistd.h within its devel files. I found this here:
http://sourceforge.net/tracker/index.php?func=detail&aid=931222&group_id=23617&atid=379173
to put it short, just make sure your compiler can reach it. in my case it's just adding "C:\GnuWin32\include" to the additional inclusion directories
use win_flex.exe with option --wincompat and you dont need to hack your lex file
unistd.h is a UNIX header, so it's not present in VC++; your best bet is probably to compile it using g++ in Cygwin (or mingw/msys). You could also look at this question for other suggestions.
I'm using flex 2.5.4 that comes from the GnuWin32 project, which doesn't check for YY_NO_UNISTD_H.
In my version, Flex looks for unistd.h only when being compiled as C++, so you can save yourself all this trouble if your yylval doesn't use any C++ constructs.
I had to use the STL in yylval (using a pointer to make it a POD type), so in order to make flex compile in C++ I created this simple unistd.h:
#include <io.h>
That's all it takes (actually, I could copy the unistd.h file that comes with GnuWin32, like flyontheweb suggests).
P.S. To wrap things up: in Bison I put yylval's required STL header files in %code requires {} and added the current directory to the INCLUDE paths in my makefile.
I am too late but anyway I will share my findings to save someone still looking for answer.
In my case having an empty unistd.h file in the location where compiler looks for headers works for me.
Well this post is old but I face the same problem and here is something that should work.
WinFlexBison
I ran into this problem recently after upgrading to Angular 14.
npm install -g latest-version
resolved my issue.
This is part of a series of at least two closely related, but distinct questions. I hope I'm doing the right thing by asking them separately.
I'm trying to get my Visual C++ 2008 app to work without the C Runtime Library. It's a Win32 GUI app without MFC or other fancy stuff, just plain Windows API.
So I set Project Properties -> Configuration -> C/C++ -> Advanced -> Omit Default Library Names to Yes (compiler flag /Zl) and rebuilt. Let's pretend I have written a suitable entry point function, which is the subject of my other question.
I get two linker errors; they are probably related. The linker complains about unresolved external symbols __fltused and _memcpy in foobar.obj. Needless to say, I use neither explicitly in my program, but I do use memcpy somewhere in foobar.cpp. (I would have used CopyMemory but that turns out to be #defined to be identical to memcpy...)
(I thought I could get rid of the memcpy problem by using a compiler intrinsic, like #pragma intrinsic(memcpy), but this makes no difference.)
If I look at the preprocessor output (adding /P to the compiler command line), I see no references to either __fltused or _memcpy in foobar.i.
So, my question is: Where do these linker errors come from, and how do I resolve them?
__fltused implies you are using or have at least declared some floats or doubles. The compiler injects this 'useless' symbol to cause a floating support .obj to get loaded from the crt. You can get around this by simply declaring a symbol with the name
#ifdef __cplusplus
extern "C" {
#endif
int _fltused=0; // it should be a single underscore since the double one is the mangled name
#ifdef __cplusplus
}
#endif
WRT _memcpy - memcpy is a __cdecl function, and all cdecl functions get an automatic _ as part of their decoration. so, when you say "__cdecl memcpy" - the compiler & linker go looking for a symbol called '_memcpy'. Intrinsic functions - even explicitly requested - can still be imported if the build settings have debug settings that contra-indicate intrinsics. So you are going to need to implement your own memcpy and related functions at some point anyway.
I recommend setting the "generate assembly listing" (or some such) compiler option for foobar.cpp once, and then inspecting the assembler code. This should really tell you where these symbols are used.
I have a set of statically-compiled libraries, with fairly deep-running dependencies between the libraries. For example, the executable X uses libraries A and B, A uses library C, and B uses libraries C and D:
X -> A
A -> C
X -> B
B -> C
B -> D
When I link X with A and B, I don't want to get errors if C and D were not also added to the list of libraries—the fact that A and B use these libraries internally is an implementation detail that X should not need to know about. Also, when new dependencies are added anywhere in the dependency tree, the project file of any program that uses A or B would have to be reconfigured. For a deep dependency tree, the list of required libraries can become really long and hard to maintain.
So, I am using the "Additional Dependencies" setting of the Librarian section in the A project, adding C.lib. And in the same section of B's project, I add C.lib and D.lib. The effect of this is that the librarian bundles C.lib into A.lib, and C.lib and D.lib into B.lib.
When I link X, however, both A.lib and B.lib contain their own copy of C.lib. This leads to tons of warnings along the lines of
A.lib(c.obj) : warning LNK4006 "symbol" (_symbol) already defined in B.lib(c.obj); second definition ignored.
How can I accomplish this without getting warnings? Is there a way to simply disable the warning, or is there a better way?
EDIT: I have seen more than one answer suggesting that, for the lack of a better alternative, I simply disable the warning. Well, this is part of the problem: I don't even know how to disable it!
As far as I know you can't disable linker warnings.
However, you can ignore some of them, using command line parameter of linker eg. /ignore:4006
Put it in your project properties under linker->command line setting (don't remember exact location).
Also read this:
Link /ignore
MSDN Forum - hiding LNK warnings
Wacek
Update If you can build all involved project in single solution, try this:
Put all project in one sln.
Remove all references to static libraries from projects' linker or librarian properties.
There is "Project Dependencies..." option in context menu for each project in Solution Explorer. Use it to define dependencies between project.
It should work. It doesn't invalidate anything I said before, the basic model of building C/C++ programs stays the same. VS (at least 2005 and newer) is simply smart enough to add all needed static libraries to linker command line. You can see it in project properties.
Of course this method won't help if you need to use already compiled static libraries. Then you need to add them all to exe or dll project that directly or indirectly uses them.
I don't think you can do anything about that. You should remove references to other static libs from static libs projects and add all needed static libs projects as dependences of exe or dll projects. You will just have to live with fact that any project that includes A.lib or B.lib also needs to include C.lib.
As an alternative you can turn your libraries into dlls which provide a richer model.
Statically compiled libraries simply aren't real libraries with dependency information, etc, like dlls. See how, when you build them, you don't really need to provide libraries they depend on? Headers are all that's needed. See? You can't even really say static libraries depend on something.
Static library is just an archive of compiled and not yet linked object code. It's not consistent whole. Each object file is compiled separately and remains separate entity inside the library. Linking happens when you build exe or dll. That's when you need to provide all object code. That's when all the symbol and dependency resolving happens.
If you add other static libraries to static library dependencies, librarian will simply copy all code together. Then, when building exe, linker will give you lots of warnings about duplicate symbols. You might be able to block those warnings (I don't know how) but be careful. It may conceal real problems like real duplicate symbols with differing definitions. And if you have static data defined in libraries, it probably won't work anyway.
Microsoft (R) Incremental Linker Version 9.00.x (link.exe) knows argument /ignore:4006
You could create one library which contains A, B, C & D and then link X against that.
Since it's a library, only object modules which are actually referenced will get linked into the final executable.
Note that one way of getting this warning is to define a member function in a header without the inline statement:
// Foo.h
class Foo
{
void someFunction();
};
void Foo:someFunction() // Warning! - should be "inline void Foo::someFunction()"
{
// do stuff
}
The problem is you are not localizing library C's symbols. So you have a ODR violation when you link in A and B. You need to have a way to make these private. By default all symbols are exported. One way to do this is to have a special linker definition file for both A and B that explicitly mention which files need to be exported.
[1] ODR = One Definition Rule.
I think the best course of action here will be to ignore/disable the linker warnings(LNK4006) since C.lib needs to be part of both A.Lib and B.lib and A.Lib does not need to know that B.lib itself uses C.Lib.
This may not fix your link error, but it might help with your dependency tree issue.
What I do, is just use a #pragma to include a lib in the .cpp file that needs it. For example:
#pragma comment(lib:"wsock32")
Like I said, I'm not sure it would keep the symbols in that object file, I'd have to whip up an example to try it out.
Poor flodin seems frustrated that nobody will explain how to disable the linker warnings. Well, I've had a similar problem, and for years I have simply lived with the fact that several hundred warnings were displayed. Now, however, thanks to the info from Link /ignore, I figured out how to disable the linker warnings.
I'm using Visual Studio 2008. In Project -> Settings -> Configuration Properties -> Librarian -> Command Line -> Additional Options, I added "/ignore:4006" (without the quotes). Now my warnings are gone!