I am downloading a text string from a web service into an RBuf8 using this kind of code (it works..)
void CMyApp::BodyReceivedL( const TDesC8& data ) {
int newLength = iTextBuffer.Length() + data.Length();
if (iTextBuffer.MaxLength() < newLength)
{
iTextBuffer.ReAllocL(newLength);
}
iTextBuffer.Append(data);
}
I want to then convert the RBuf8 into a char* string I can display in a label or whatever.. or for the purposes of debug, display in
RDebug::Printf("downloading text %S", charstring);
edit for clarity..
My conversion function looks like this..
void CMyApp::DownloadCompleteL() {
{
RBuf16 buf;
buf.CreateL(iTextBuffer.Length());
buf.Copy(iTextBuffer);
RDebug::Printf("downloaded text %S", buf);
iTextBuffer.SetLength(0);
iTextBuffer.ReAlloc(0);
}
But this still causes a crash. I am using S60 3rd Edition FP2 v1.1
What you may need is something to the effect of:
RDebug::Print( _L( "downloaded text %S" ), &buf );
This tutorial may help you.
void RBuf16::Copy(const TDesC8&) will take an 8bit descriptor and convert it into a 16bit descriptor.
You should be able to display any 16bit descriptor on the screen. If it doesn't seem to work, post the specific API you're using.
When an API can be used with an undefined number of parameters (like void RDebug::Printf(const char*, ...) ), %S is used for "pointer to 16bit descriptor". Note the uppercase %S.
Thanks, the %S is a helpful reminder.
However, this doesn't seem to work.. my conversion function looks like this..
void CMyApp::DownloadCompleteL() {
{
RBuf16 buf;
buf.CreateL(iTextBuffer.Length());
buf.Copy(iTextBuffer);
RDebug::Printf("downloaded text %S", buf);
iTextBuffer.SetLength(0);
iTextBuffer.ReAlloc(0);
}
But this still causes a crash. I am using S60 3rd Edition FP2 v1.1
You have to supply a pointer to the descriptor in RDebuf::Printf so it should be
RDebug::Print(_L("downloaded text %S"), &buf);
Although use of _L is discouraged. _LIT macro is preferred.
As stated by quickrecipesonsymbainosblogspotcom, you need to pass a pointer to the descriptor.
RDebug::Printf("downloaded text %S", &buf); //note the address-of operator
This works because RBuf8 is derived from TDes8 (and the same with the 16-bit versions).
Related
A bit of foreground: my task required converting UTF-8 XML file to UTF-16 (with proper header, of course). And so I searched about usual ways of converting UTF-8 to UTF-16, and found out that one should use templates from <codecvt>.
But now when it is deprecated, I wonder what is the new common way of doing the same task?
(Don't mind using Boost at all, but other than that I prefer to stay as close to standard library as possible.)
Don't worry about that.
According to the same information source:
this library component should be retired to Annex D, along side ,
until a suitable replacement is standardized.
So, you can still use it until a new standardized, more-secure version is done.
std::codecvt template from <locale> itself isn't deprecated. For UTF-8 to UTF-16, there is still std::codecvt<char16_t, char, std::mbstate_t> specialization.
However, since std::wstring_convert and std::wbuffer_convert are deprecated along with the standard conversion facets, there isn't any easy way to convert strings using the facets.
So, as Bolas already answered: Implement it yourself (or you can use a third party library, as always) or keep using the deprecated API.
Since nobody really answers the question and provides usable replacement code, here is one but it's only for Windows:
#include <string>
#include <stdexcept>
#include <Windows.h>
std::wstring string_to_wide_string(const std::string& string)
{
if (string.empty())
{
return L"";
}
const auto size_needed = MultiByteToWideChar(CP_UTF8, 0, &string.at(0), (int)string.size(), nullptr, 0);
if (size_needed <= 0)
{
throw std::runtime_error("MultiByteToWideChar() failed: " + std::to_string(size_needed));
}
std::wstring result(size_needed, 0);
MultiByteToWideChar(CP_UTF8, 0, &string.at(0), (int)string.size(), &result.at(0), size_needed);
return result;
}
std::string wide_string_to_string(const std::wstring& wide_string)
{
if (wide_string.empty())
{
return "";
}
const auto size_needed = WideCharToMultiByte(CP_UTF8, 0, &wide_string.at(0), (int)wide_string.size(), nullptr, 0, nullptr, nullptr);
if (size_needed <= 0)
{
throw std::runtime_error("WideCharToMultiByte() failed: " + std::to_string(size_needed));
}
std::string result(size_needed, 0);
WideCharToMultiByte(CP_UTF8, 0, &wide_string.at(0), (int)wide_string.size(), &result.at(0), size_needed, nullptr, nullptr);
return result;
}
The new way is... you write it yourself. Or just rely on deprecated functionality. Hopefully, the standards committee won't actually remove codecvt until there is a functioning replacement.
But at present, there isn't one.
I'm been trying to start doing a plug-in for a program called "Euroscope" for quite some time and i still can't do anything. I even read a C++ book and nothing, it's too difficult to start.
The question i'm going to ask is a little bit specific and it's going to be difficult to explain but i'm tired of trying to solve this by my own so here it comes.
I have a class that i imported with a bunch of function prototypes in the header called "EuroscopePlugIn".
My principal .cpp is this:
void CPythonPlugInScreen::meu()
{
//loop over the planes
EuroScopePlugIn::CAircraft ac;
EuroScopePlugIn::CAircraftFlightPlan acfp;
CString str;
CPythonPlugIn object;
for(ac=GetPlugIn()->AircraftSelectFirst();
ac.IsValid();
ac=GetPlugIn()->AircraftSelectNext(ac))
{
EuroScopePlugIn::CAircraftPositionData acpos=ac.GetPosition();
const char *c=ac.GetCallsign();
object.printtofile_simple_char(*c);
object.printtofile_simple_int(ac.GetState());
};
object.printtofile_simple_int(ac.GetVerticalSpeed());
object.printtofile_simple_int(acfp.GetFinalAltitude());
cout<<acfp.GetAlternate();
}
the "printtofile_simple_int" and "printtofile_simple_char" are defined is the class CPythonPlugIn like this:
void printtofile_simple_int(int n){
ofstream textfile;
textfile.open("FP_simple_int.txt");
textfile<<(n);
textfile.close();
So i open the program, load the .dll i created with Build->Solution and it does nothing, the .txt files aren't even created and even the cout produces nothing.
I will give you some of the prototype infos on the header file "EuroScopePlugIn.h" in case you need them to understand my micro program. If you need other,ask me and i'll put it here
//---GetPlugIn-----------------------------------------------------
inline CPlugIn * GetPlugIn ( void )
{
return m_pPlugIn ;
} ;
&
CAircraft AircraftSelectFirst ( void ) const ;
//-----------------------------------------------------------------
// Return :
// An aircraft object instance.
//
// Remark:
// This instance is only valid inside the block you are querying.
// Do not save it to a static place or into a member variables.
// Subsequent use of an invalid extracted route reference may
// cause ES to crash.
//
// Description :
// It selects the first AC in the list.
//-----------------------------------------------------------------
&
int GetFinalAltitude ( void ) const ;
//-----------------------------------------------------------------
// Return :
// The final requested altitude.
//-----------------------------------------------------------------
Please guys i need help to start with the plug-in making, from that point on with a methodology of trial and error i'll be on my way. I'm just finding it extremely hard to start...
Thank you very much for the help
IDWriteTextFormat::SetTextAlignment was used to alignment text in DirectWrite, it takes a parameter of DWRITE_TEXT_ALIGNMENT type
enum DWRITE_TEXT_ALIGNMENT {
DWRITE_TEXT_ALIGNMENT_LEADING,
DWRITE_TEXT_ALIGNMENT_TRAILING,
DWRITE_TEXT_ALIGNMENT_CENTER,
DWRITE_TEXT_ALIGNMENT_JUSTIFIED
};
the first 3 type all work well, but the last one DWRITE_TEXT_ALIGNMENT_JUSTIFIED does not work, when I try to set it, I got an invalid argument error
HRESULT hr = g_pTextFormat->SetTextAlignment(DWRITE_TEXT_ALIGNMENT_JUSTIFIED);
if(FAILED(hr))
{
MessageBox(NULL, L"Center text failed!", L"Error", 0);
return;
}
It seems this is not a valid argument, why? does anyone encountered the same issue?
Got the answer from Microsoft DirectX forum, it is because, this flag does not support Win7, but the SDK document does not point it out.
http://xboxforums.create.msdn.com/forums/p/108456/640004.aspx#640004
I am just trying to compile a bit bigger project using the Visual Studio 2012 Release Candidate, C++. The project was/is compiled using the VS2010 now. (I am just greedy to get the C++11 things, so I tried. :)
Apart of things that I can explain by myself, the project uses the code like this:
ostringstream ostr;
ostr << "The " __FUNCTION__ "() failed to malloc(" << i << ").";
throw bad_alloc(ostr.str().c_str());
The compiler now complains
error C2248: 'std::bad_alloc::bad_alloc' : cannot access private member declared
in class 'std::bad_alloc'
... which is true. That version of constructor is now private.
What was the reason to make that version of constructor private? Is it recommended by C++11 standard not to use that constructor with the argument?
(I can imagine that if allocation failed, it may cause more problems to try to construct anything new. However, it is only my guess.)
Thanks,
Petr
The C++11 Standard defines bad_alloc as such (18.6.2.1):
class bad_alloc : public exception {
public:
bad_alloc() noexcept;
bad_alloc(const bad_alloc&) noexcept;
bad_alloc& operator=(const bad_alloc&) noexcept;
virtual const char* what() const noexcept;
};
With no constructor that takes a string. A vendor providing such a constructor would make the code using it not portable, as other vendors are not obliged to provide it.
The C++03 standard defines a similar set of constructors, so VS didn't follow this part of the standard even before C++11. MS does try to make VS as standard compliant as possible, so they've probably just used the occasion (new VS, new standard) to fix an incompatibility.
Edit: Now that I've seen VS2012's code, it is also clear why the mentioned constructor is left private, instead of being completely removed: there seems to be only one use of that constructor, in the bad_array_new_length class. So bad_array_new_length is declared a friend in bad_alloc, and can therefore use that private constructor. This dependency could have been avoided if bad_array_new_length just stored the message in the pointer used by what(), but it's not a lot of code anyway.
If you are accustomed to passing a message when you throw a std::bad_alloc, a suitable technique is to define an internal class that derives from std::bad_alloc, and override ‘what’ to supply the appropriate message.
You can make the class public and call the assignment constructor directly, or make a helper function, such as throw_bad_alloc, which takes the parameters (and additional scalar information) and stores them in the internal class.
The message is not formatted until ‘what’ is called. In this way, stack unwinding may have freed some memory so the message can be formatted with the actual reason (memory exhaustion, bad request size, heap corruption, etc.) at the catch site. If formatting fails, simply assign and return a static message.
Trimmed example:
(Tip: The copy constructor can just assign _Message to nullptr, rather than copy the message since the message is formatted on demand. The move constructor, of course can just confiscate it :-).
class internal_bad_alloc: public std::bad_alloc
{
public:
// Default, copy and move constructors....
// Assignment constructor...
explicit internal_bad_alloc(int errno, size_t size, etc...) noexcept:
std::bad_alloc()
{
// Assign data members...
}
virtual ~internal_bad_alloc(void) noexcept
{
// Free _Message data member (if allocated).
}
// Override to format and return the reason:
virtual const char* what(void) const noexcept
{
if (_Message == nullptr)
{
// Format and assign _Message. Assign the default if the
// format fails...
}
return _Message;
}
private:
// Additional scalar data (error code, size, etc.) pass into the
// constructor and used when the message is formatted by 'what'...
mutable char* _Message;
static char _Default[];
}
};
//
// Throw helper(s)...
//
extern void throw_bad_alloc(int errno, size_t size, etc...)
{
throw internal_bad_alloc(errno, size, etc...);
}
I'm currently working on a metro app that requires a few textual resources. Part of the build process is copying all of these resources to a folder inside of the app's installation directory. What I'd like to do is gather a list of these resource files, and process each one accordingly. Unfortunately, my attempts to do so have been less than successful.
Since I'm building for WinRT, I can't use the very useful "FindFirstFile" and "FindNextFile" functions. I've been trying to get the job done using the WinRT Asynchronous file IO operations.
auto getResourceFolder = installedLocation->GetFolderFromPathAsync( folderPath );
getResourceFolder->Completed = ref new Windows::Foundation::AsyncOperationCompletedHandler< Windows::Storage::StorageFolder^ >(
[this]( Windows::Foundation::IAsyncOperation< Windows::Storage::StorageFolder^ >^ operation ) {
if( operation->Status == Windows::Foundation::AsyncStatus::Completed ) {
auto resourceFolder = operation->GetResults();
auto getResourceFiles = resourceFolder->GetFilesAsync();
getResourceFiles->Completed = ref new Windows::Foundation::AsyncOperationCompletedHandler< IVectorView< Windows::Storage::IStorageFile^ >^ >(
[this]( Windows::Foundation::IAsyncOperation< IVectorView< Windows::Storage::IStorageFile^ >^ >^ operation ) {
if( operation->Status == Windows::Foundation::AsyncStatus::Completed ) {
auto resourceFiles = operation->GetResults();
for( unsigned int i = 0; i < resourceFiles->Size; ++i ) {
// Process File
}
}
});
}
});
Which fails to compile:
error C2664: 'Windows::Foundation::IAsyncOperation<TResult>::Completed::set' : cannot convert parameter 1 from 'Windows::Foundation::AsyncOperationCompletedHandler<TResult> ^' to 'Windows::Foundation::AsyncOperationCompletedHandler<TResult> ^'
The error isn't making any sense to me. I've tried rewriting the above code so that the lambda handler functions are not inline, but it hasn't made a difference. I'm not sure what's wrong.
Any ideas? Thanks in advance.
[Note: I have omitted most namespace qualification from the code and error messages for brevity.]
The Visual Studio Error List pane only shows the first line of each error (this is a very useful feature, especially when programming in C++, because some error messages from the compiler are exceedingly long. You need to look at the Output window to see the rest of the error message:
error C2664: 'IAsyncOperation<TResult>::Completed::set' :
cannot convert parameter 1
from 'AsyncOperationCompletedHandler<TResult> ^'
to 'AsyncOperationCompletedHandler<TResult> ^'
with
[
TResult=IVectorView<StorageFile ^> ^
]
and
[
TResult=IVectorView<IStorageFile ^> ^
]
and
[
TResult=IVectorView<StorageFile ^> ^
]
No user-defined-conversion operator available, or
Types pointed to are unrelated;
conversion requires reinterpret_cast, C-style cast or function-style cast
This is still a bit confusing because all three templates use a parameter named TResult. To decipher the error, note that the order of the templates in the first line matches the order of the template argument lists in the rest of the line.
The issue here is that you are mixing usage of StorageFile and IStorageFile. On both of these lines, you need to use StorageFile (see carrots under lines for where IStorageFile is used):
getResourceFiles->Completed = ref new Windows::Foundation::AsyncOperationCompletedHandler< IVectorView< Windows::Storage::IStorageFile^ >^ >(
^
[this]( Windows::Foundation::IAsyncOperation< IVectorView< Windows::Storage::IStorageFile^ >^ >^ operation ) {
^
Note that once you fix this issue, you'll get another pair of errors because your lambdas need to have two parameters; the second is an AsyncStatus. In the end, they should both be declared as:
// Namespaces omitted for brevity
[this](IAsyncOperation<StorageFolder^>^ operation, AsyncStatus status) { }
Since I'm building for WinRT, I can't use the very useful FindFirstFile and FindNextFile functions.
Note that you can, in fact, use both FindFirstFileEx and FindNextFile in a Metro style app. (The non-Ex FindFirstFile is not usable).
You should use the asynchronous WinRT functions wherever you can and wherever it is practical, but that doesn't mean there isn't still a use for these other functions.
A far simpler solution is to use PPL for your async operations. Instead of manually rolling the async operation, try:
create_task(installedLocation->GetFolderFromPathAsync(folderPath)
.then([this](Windows::Storage::StorageFolder^ folder) {
return folder->GetFilesAsync();
})
.then([this](IVectorView<Windows::Storage::StorageFile^ >^ files) {
for( unsigned int i = 0; i < files->Size; ++i ) {
// Process File
}
});
I'm not 100% on the syntax, this was written in the SO code editor, but it shows how PPL dramatically reduces the complexity of this kind of code - basically you use create_task to create a task, then use the .then method on the task to specify a lambda which is used for async completion.
EDIT: Updated to remove the nested lambda.