I am getting a compilation error when trying to build a C++ project which previously worked.
The code follows:
const wchar_t* pdest;
pdest = _tcsstr(ConnStr, Name);
The error follows:
Error 10 error C2440: '=' : cannot convert from 'const char *' to 'const wchar_t
I'm using Visual Studio 2008. The error message explains the problem well, but I know this program used to compile, what am I doing wrong?
Your code is dangerous. _tcsstr is a TCHAR macro, so it's definition can change depending on whether or not UNICODE is defined. wchar_t is fixed. The error you're seeing is due to this exact problem - the environment is using the single-byte version of _tcsstr (likely becasue UNICODE is not defined).
Don't just define UNICODE. Fix the code first. Either use TCHAR macros for both, or the wide character functions.
_tcsstr is for use with TCHAR. Depending on compile settings, this is either char or wchar_t.
So either use TCHAR, or wcsstr
That should fix this issue:
Property -> Configuration Properties -> General -> Character Set : Use multi-Byte Character Set.
Related
Using VS2017 I compile the code below using the unicode character set
STDMETHODIMP Load(LPCOLESTR lpwszFileName, const AM_MEDIA_TYPE *pmt) {
TCHAR *szExtension = PathFindExtension(lpwszFileName);
and I get the following error
error C2664: 'LPSTR PathFindExtensionA(LPCSTR)': cannot convert argument 1 from 'LPCOLESTR' to 'LPCSTR'
The same code under VS2008 compiles just fine. What seems to be to problem here and why the compiler chooses the ANSI version of the PathFindExtenstion instead of the unicode one ?
The problem was that the VS2017 variable
%(PreprocessorDefinitions)
was missing from Preprocessor Definitions. Now the definers /D _UNICODE and /D UNICODE are added correctly to the compiler parameter's list.
I'm trying to set up an arduino uno for serial port communication with a C++ program in visual studio 2010. I'm working from the code found here: http://playground.arduino.cc/Interfacing/CPPWindows
Unfortunately, the .cpp file gives me the following message for line 9 for the variable 'portName':
Error: argument of type "char *" is incompatible with parameter of type "LPCWSTR"
I don't understand this error message, and have tried a few different things to fix it. Any help would be greatly appreciated!
Given the code link in your question, it seems the problem is here:
Serial::Serial(char *portName)
{
...
this->hSerial = CreateFile(portName, // <--- ERROR
CreateFile is a Win32 API that expects an LPCTSTR as first string parameter .
LPCTSTR is a Win32 typedef, which is expanded to:
const char* in ANSI/MBCS builds
const wchar_t* in Unicode builds (which have been the default since VS2005)
Since you are using VS2010, probably you are in the default Unicode build mode.
Actually, there is no "physical" CreateFile API exposed, but there are two distinct functions: CreateFileA and CreateFileW. The former takes a const char* input string, the latter takes a const wchar_t*.
In Unicode builds, CreateFile is a preprocessor macro expanded to CreateFileW; in ANSI/MBCS builds, CreateFile is expanded to CreateFileA.
So, if you are in Unicode build mode, your CreateFile call is expanded to CreateFileW(const wchar_t*, ...). Since portName is defined as a char*, there is a mismatch between wchar_t* and char*, and you get a compiler error.
To fix that, you have some options.
For example, you could be explicit in your code, and just call CreateFileA() instead of CreateFile(). In this way, you will be using the ANSI/MBCS version of the function (i.e., the one taking a const char*), independently from the actual ANSI/MBCS/Unicode settings in Visual Studio.
Another option would be to change your current build settings from the default Unicode mode to ANSI/MBCS. To do that, you can follow the path:
Project Properties | Configuration Properties | General | Character Set
and select "Use Multi-Byte Character Set", as showed in the following screenshot:
Your settings in Visual Studio are probably set to Unicode but the code you're compiling expects ASCII.
Go to Project Properties -> Configuration Properties -> General -> Character Set and choose "Use Multi-Byte Character Set".
-Surenthar
Your settings in Visual Studio are probably set to Unicode but the code you're compiling expects ASCII.
Go to Project Properties -> Configuration Properties -> General -> Character Set and choose "Use Multi-Byte Character Set".
You should also remove UNICODE or _UNICODE from C++ -> Preprocessor -> Preprocessor definitions, if they are defined there.
This will make your code call the ASCII versions of the Windows API functions, which accept char strings.
I have been using this:
char appdata[250];
ExpandEnvironmentStrings("%AppData%\\\MCPCModLocator\\", appdata, 250);
in C++ Win32 to get the AppData folder on one of my projects. Its worked fine, no issues. Now on my newest project (same PC, still in Visual Studio 2013) when I try to do that, i get an error on the first string saying "const char* is incompatible with type LPCWSTR" and on the second parameter it says "char * is incompatible with type LPWSTR". I have no idea why it work on the first project, but not the second. I assume its a setting change, but looking through each projects settings, I see nothing. Any help is appreciated! Thanks!
ExpandEnvironmentStrings is a macro that expands to ExpandEnvironmentStringsA or ExpandEnvironmentStringsW depending on whether UNICODE was defined when you included <windows.h>.
In a Visual Studio project UNICODE is defined by default, but this is not so for command line use of the compiler.
Since modern Windows programming is better based on Unicode, the best fix is not to remove the definition of UNICODE but to add an L prefix to your literals, like L"Hello", which makes it a “wide” wchar_t based literal, and correspondingly change the type of appdata.
By default, newly created project in VS2013 has been set to use Unicode APIs, those use LPWSTR (or, wchar_t*) instead of LPSTR(or, char*).
You can call the old ANSI version APIs by add "A" at the end of function name explicitly e.g. ExpandEnvironmentStringsA or change the project configuration to use Multibyte character set(Project Property pages -> configuration properties -> general -> character set)
I have two projects with almost the same configuration in visual studio 2010
One with the console works and gives no trouble with the statement
SharedAppenderPtr myAppender(new FileAppender("myLogFile.log"));
While the other project a dll project gives trouble with the same statement
SharedAppenderPtr myAppender(new FileAppender("myLogFile.log"));
The error message is:
Error 3 error C2664: 'log4cplus::FileAppender::FileAppender(const log4cplus::tstring &,std::ios_base::openmode,bool)' : cannot convert parameter 1 from 'const char [10]' to 'const log4cplus::tstring &'
Any suggestions on how I could resolve this issue ?
Try wrapping the "myLogFile.log" like this: LOG4CPLUS_TEXT("myLogFile.log"). You could also use the _T() macro, since you are on Windows with Visual Studio.
I don't know what type log4cplus::tstring is but assuming it is a typedef for a type similar to std::basic_string<cT> (possibly even std::basic_string<cT> with a type cT other than char) you might try one of these:
SharedAppenderPtr app1(new FileAppender(L"myLogFile.log"));
std::string name("myLogFile.log");
SharedApppenderPtr app2(new FileAppender(log4cplus::tstring(name.begin(), name.end())));
Trying to compile this old VC++ 6.0 program in VC++ 2010. This ATL/WTL stuff is giving me lots of problems. I downloaded and have linked to the latest WTL (as far as I know) wtl71.
I am getting compile errors in atlmisc.h:
atlmisc.h(1159): error C2440: 'return' : cannot convert from 'const char *' to 'TCHAR *'
I've searched the 'net, and the answers that come up call for modifying the stock MS atlmisc.h file!
Am I missing something here? What do I need to do to get this to compile?
Most of the time I've seen that error, it's because I've been trying to build a Unicode application. In a Unicode application, the TCHAR* is a short* or wchar_t* rather than a char*.
I'd suggest checking your project settings and making sure that in the project properties, General > Character Set is set to Use Multi-Byte Character Set.