QT Can not write to a unicode file unicode strings - qt

I am using QT Creator, created a console app. Everything is up to date. OS is Windows XP.
I have created a QString that holds some Hungarian chars. Most of the Hungarian chars do not require unicode but the chars that have double slashes for accents require unicode.
I try to write the QString contents to a file but my unicode chars lose their accents in the file. In other words, the unicode info is lost along the way.
My code is bellow.
#include <QtCore/QCoreApplication>
#include <QString>
#include <QTextStream>
#include <QDate>
#include <QFile>
using namespace std;
int main(int argc, char *argv[])
{
QCoreApplication app(argc, argv);
QString szqLine = "NON-UnicodeIsOK: áéüúöóí NEED-Unicode: űő";
//These are Hungarian chars and require unicode. Actually, only the u & o, each having double
//slashes for eccents require unicode encoding.
//Open file for writing unicode chars to.
QFile file("out.txt");
if ( !file.open(QIODevice::WriteOnly | QIODevice::Text) ){
return 1;
}
//Stream the QString text to the file.
QTextStream out(&file);
out.setCodec("UTF-8");
out << szqLine << endl; //Use endl for flush. Does not properly write ű and ő chars.
//Accents missing in file.
file.close(); //Done with file.
return app.exec();
}

What is the encoding of your file? Using non-ascii encodings in source files often causes problems, at least when working cross-platform. I think MSVC has some problems there.
QString foo = "unicode string" uses the implicit conversion from ascii to unicode, which will also cause problems. Always explicitely specify what encoding the literal uses, e.g. by wrapping the literal using QLatin1String() if it's latin1:
QString foo = QLatin1String("some latin1 string");
or, utf-8, as it should be in your case, QString::fromUtf8():
QString foo = QString::fromUtf8( "funny characters" );
Before writing the string to a file (which is another source for possible errors, although your code looks correct), check if a qt widget (QLineEdit, for example) displays it correctly.
To avoid such errors, I prefer to keep source files pure ascii, with english strings, and then translate them using Qt's internationalization tools.
Edit: Also see the accepted answer to this question about UTF-8 literals in MSVC 2008.

Are you sure that szqLine really contains the correct characters?
Try this: QString line = QString::fromStdWString(L"NON-UnicodeIsOK: \x00E1\x00E9... NEED-Unicode: \x+0171\x0151";
... and don't use Hungarian notation ;-)

Related

How to make a c++ code can be used in both Qt project (QTL style) and C++ project (STL style)

Is there any way to convert C++(STL) code to QT (QTL)?
I have a code written using STL (string, vector, iostream, fstream) and
I want to add it to my Qt Project (QString, QVector, ... when used).
My ideal way is to make it QTL-STL-compatible by adding some defines
in .h file like following
// STL to QTL
#ifdef STL_CPP
#include <string>
#include<vector>
#else // QTL
#include <QString>
#define string QString
#include <QVector>
#define vector QVector
#endif
Is there any existing work can convert some most commonly used STL code without
changing the source code ?
Note that I don't want to convert std datatype to qt datatype, what I want is to
make a code can used in both Qt project(ifndef STL_CPP) and C++ project (ifdef STL_CPP).
Using Macro Substitution to convert STL-style code to QTL-style code is dangerous
and may cause many unexpected errors.
To avoid that, you can use the STL in QT code and convert when interacting with the Qt framework (for a price paid in performance),
convert STL datatype to QTL datatype is quite simple, just like QVector::fromStdVector(const std::vector<T> &vector) and QString::fromStdString(const std::string &str) mentioned by drescherjm

Qt's QDir: File Names Dropping Non-Ascii Characters

I am having issues with QDir losing Non-Ascii characters from my file names.
I have files with names like testingöäüß.txt or exampleΦ.shp and when trying to use Qt utilities like QDir and QFile they simply show up as testing.txt and example.shp. Seems as though I cannot tell those classes what kind of encoding to use. I'm trying QDirIterator and the QDir function entryInfoList:
QDir someDir("/home/blah"); //contains testingöäüß.txt
QDirIterator dirIter(someDir.absolutePath(), QDir::NoDotAndDotDot | QDir::Dirs | QDir::Files);
while(dirIter.hasNext())
{
QString fileName1 = QFile::decodeName(dirIter.next().toUtf8());
std::cout << "QDirIterator Name " << fileName1.toStdString().c_str() << std::endl;
}
QFileInfoList fileInfoList = someDir.entryInfoList(QDir::NoDotAndDotDot | QDir::Dirs | QDir::Files);
foreach(QFileInfo fileInfo, fileInfoList)
{
QString fileName1 = QFile::decodeName(fileInfo.fileName().toUtf8());
std::cout << "entryInfoList Name " << fileName1.toStdString().c_str() << std::endl;
QString fileName2 = QFile::decodeName(fileInfo.absoluteFilePath().toUtf8());
std::cout << "entryInfoList Name2 " << fileName2.toStdString().c_str() << std::endl;
QString fileName3 = QString::fromUtf8(dirIter.fileInfo().absoluteFilePath().toStdString().c_str());
std::cout << "entryInfoList Name3 " << fileName3.toStdString().c_str() << std::endl;
}
Every one of those prints will lack the non-ascii characters. Seems like as soon as you try to grab the file names to loop over they will be ascii only. Anyone have any ideas on this? Or can Qt simply not handle this? Thanks!
I know this is an old question, but I just ran into the same problem. The same exact Qt code would work fine on my development VM, but when I transferred it to an embedded Linux system (running on x86 so literally the same executable) my directory names just silently got their non-ASCII characters dropped.
Turned out the QTextCodec::codecForLocale on my dev VM was set to UTF-8, and on the embedded box it was System. If I manually changed the locale to UTF-8 before doing any filesystem operations (by calling QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"))), everything started working fine.
So why was this happening in the first place? My suspicion is that in the process of slimming down the embedded system's root filesystem I might have accidentally deleted some locale-related files that Qt was using to try to auto-detect the locale. When it couldn't determine it was on UTF-8, it fell back to System, which for whatever reason is broken (maybe for the same reason it couldn't detect UTF-8 in the first place).
I need to eventually fix whatever is causing it to not auto-detect, but in the short-term just manually setting a UTF-8 locale should work if you are experiencing this same issue.
Note that this has nothing to do with whether the console can display UTF-8, or anything to do with manual conversion of UTF-16 to UTF-8! So Felix's answer to this question is not correct, at least for this particular issue. To completely remove the capability of the console from the equation, I was also simply printing the number of UTF-16 characters in the string, and every non-ASCII character actually made the returned path and filename strings from QDir::entryInfoList have one less UTF-16 character. Additionally, the dead giveaway is that the characters were simply stripped out, not just replaced with garbage or question marks or whatever.
Qt can handle filenames with special characters. You just make them disappear somewhere in that string conversion stuff. (Which is completly unnecessary) Try it this way:
#include <QDebug>
//...
QFileInfoList fileInfoList = someDir.entryInfoList(QDir::NoDotAndDotDot | QDir::Dirs | QDir::Files);
foreach(QFileInfo fileInfo, fileInfoList)
{
qDebug() << fileInfo.fileName();//uses qdebug
std::cout << fileInfo.fileName().toStdWString() << std::endl;//uses a 16Bit string on normal cout
}
If you still don't see them, it's because your console settings do not allow to display them. Try to write them to a file or display them in a gui - or simply try to open a file with that name, it will work.

Is there a way for a C binary code to figure out where it is stored? [duplicate]

Is there a platform-agnostic and filesystem-agnostic method to obtain the full path of the directory from where a program is running using C/C++? Not to be confused with the current working directory. (Please don't suggest libraries unless they're standard ones like clib or STL.)
(If there's no platform/filesystem-agnostic method, suggestions that work in Windows and Linux for specific filesystems are welcome too.)
Here's code to get the full path to the executing app:
Variable declarations:
char pBuf[256];
size_t len = sizeof(pBuf);
Windows:
int bytes = GetModuleFileName(NULL, pBuf, len);
return bytes ? bytes : -1;
Linux:
int bytes = MIN(readlink("/proc/self/exe", pBuf, len), len - 1);
if(bytes >= 0)
pBuf[bytes] = '\0';
return bytes;
If you fetch the current directory when your program first starts, then you effectively have the directory your program was started from. Store the value in a variable and refer to it later in your program. This is distinct from the directory that holds the current executable program file. It isn't necessarily the same directory; if someone runs the program from a command prompt, then the program is being run from the command prompt's current working directory even though the program file lives elsewhere.
getcwd is a POSIX function and supported out of the box by all POSIX compliant platforms. You would not have to do anything special (apart from incliding the right headers unistd.h on Unix and direct.h on windows).
Since you are creating a C program it will link with the default c run time library which is linked to by ALL processes in the system (specially crafted exceptions avoided) and it will include this function by default. The CRT is never considered an external library because that provides the basic standard compliant interface to the OS.
On windows getcwd function has been deprecated in favour of _getcwd. I think you could use it in this fashion.
#include <stdio.h> /* defines FILENAME_MAX */
#ifdef WINDOWS
#include <direct.h>
#define GetCurrentDir _getcwd
#else
#include <unistd.h>
#define GetCurrentDir getcwd
#endif
char cCurrentPath[FILENAME_MAX];
if (!GetCurrentDir(cCurrentPath, sizeof(cCurrentPath)))
{
return errno;
}
cCurrentPath[sizeof(cCurrentPath) - 1] = '\0'; /* not really required */
printf ("The current working directory is %s", cCurrentPath);
This is from the cplusplus forum
On windows:
#include <string>
#include <windows.h>
std::string getexepath()
{
char result[ MAX_PATH ];
return std::string( result, GetModuleFileName( NULL, result, MAX_PATH ) );
}
On Linux:
#include <string>
#include <limits.h>
#include <unistd.h>
std::string getexepath()
{
char result[ PATH_MAX ];
ssize_t count = readlink( "/proc/self/exe", result, PATH_MAX );
return std::string( result, (count > 0) ? count : 0 );
}
On HP-UX:
#include <string>
#include <limits.h>
#define _PSTAT64
#include <sys/pstat.h>
#include <sys/types.h>
#include <unistd.h>
std::string getexepath()
{
char result[ PATH_MAX ];
struct pst_status ps;
if (pstat_getproc( &ps, sizeof( ps ), 0, getpid() ) < 0)
return std::string();
if (pstat_getpathname( result, PATH_MAX, &ps.pst_fid_text ) < 0)
return std::string();
return std::string( result );
}
If you want a standard way without libraries: No. The whole concept of a directory is not included in the standard.
If you agree that some (portable) dependency on a near-standard lib is okay: Use Boost's filesystem library and ask for the initial_path().
IMHO that's as close as you can get, with good karma (Boost is a well-established high quality set of libraries)
I know it is very late at the day to throw an answer at this one but I found that none of the answers were as useful to me as my own solution. A very simple way to get the path from your CWD to your bin folder is like this:
int main(int argc, char* argv[])
{
std::string argv_str(argv[0]);
std::string base = argv_str.substr(0, argv_str.find_last_of("/"));
}
You can now just use this as a base for your relative path. So for example I have this directory structure:
main
----> test
----> src
----> bin
and I want to compile my source code to bin and write a log to test I can just add this line to my code.
std::string pathToWrite = base + "/../test/test.log";
I have tried this approach on Linux using full path, alias etc. and it works just fine.
NOTE:
If you are on windows you should use a '\' as the file separator not '/'. You will have to escape this too for example:
std::string base = argv[0].substr(0, argv[0].find_last_of("\\"));
I think this should work but haven't tested, so comment would be appreciated if it works or a fix if not.
Filesystem TS is now a standard ( and supported by gcc 5.3+ and clang 3.9+ ), so you can use current_path() function from it:
std::string path = std::experimental::filesystem::current_path();
In gcc (5.3+) to include Filesystem you need to use:
#include <experimental/filesystem>
and link your code with -lstdc++fs flag.
If you want to use Filesystem with Microsoft Visual Studio, then read this.
No, there's no standard way. I believe that the C/C++ standards don't even consider the existence of directories (or other file system organizations).
On Windows the GetModuleFileName() will return the full path to the executable file of the current process when the hModule parameter is set to NULL. I can't help with Linux.
Also you should clarify whether you want the current directory or the directory that the program image/executable resides. As it stands your question is a little ambiguous on this point.
On Windows the simplest way is to use the _get_pgmptr function in stdlib.h to get a pointer to a string which represents the absolute path to the executable, including the executables name.
char* path;
_get_pgmptr(&path);
printf(path); // Example output: C:/Projects/Hello/World.exe
Maybe concatenate the current working directory with argv[0]? I'm not sure if that would work in Windows but it works in linux.
For example:
#include <stdio.h>
#include <unistd.h>
#include <string.h>
int main(int argc, char **argv) {
char the_path[256];
getcwd(the_path, 255);
strcat(the_path, "/");
strcat(the_path, argv[0]);
printf("%s\n", the_path);
return 0;
}
When run, it outputs:
jeremy#jeremy-desktop:~/Desktop$ ./test
/home/jeremy/Desktop/./test
For Win32 GetCurrentDirectory should do the trick.
You can not use argv[0] for that purpose, usually it does contain full path to the executable, but not nessesarily - process could be created with arbitrary value in the field.
Also mind you, the current directory and the directory with the executable are two different things, so getcwd() won't help you either.
On Windows use GetModuleFileName(), on Linux read /dev/proc/procID/.. files.
Just my two cents, but doesn't the following code portably work in C++17?
#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;
int main(int argc, char* argv[])
{
std::cout << "Path is " << fs::path(argv[0]).parent_path() << '\n';
}
Seems to work for me on Linux at least.
Based on the previous idea, I now have:
std::filesystem::path prepend_exe_path(const std::string& filename, const std::string& exe_path = "");
With implementation:
fs::path prepend_exe_path(const std::string& filename, const std::string& exe_path)
{
static auto exe_parent_path = fs::path(exe_path).parent_path();
return exe_parent_path / filename;
}
And initialization trick in main():
(void) prepend_exe_path("", argv[0]);
Thanks #Sam Redway for the argv[0] idea. And of course, I understand that C++17 was not around for many years when the OP asked the question.
Just to belatedly pile on here,...
there is no standard solution, because the languages are agnostic of underlying file systems, so as others have said, the concept of a directory based file system is outside the scope of the c / c++ languages.
on top of that, you want not the current working directory, but the directory the program is running in, which must take into account how the program got to where it is - ie was it spawned as a new process via a fork, etc. To get the directory a program is running in, as the solutions have demonstrated, requires that you get that information from the process control structures of the operating system in question, which is the only authority on this question. Thus, by definition, its an OS specific solution.
#include <windows.h>
using namespace std;
// The directory path returned by native GetCurrentDirectory() no end backslash
string getCurrentDirectoryOnWindows()
{
const unsigned long maxDir = 260;
char currentDir[maxDir];
GetCurrentDirectory(maxDir, currentDir);
return string(currentDir);
}
For Windows system at console you can use system(dir) command. And console gives you information about directory and etc. Read about the dir command at cmd. But for Unix-like systems, I don't know... If this command is run, read bash command. ls does not display directory...
Example:
int main()
{
system("dir");
system("pause"); //this wait for Enter-key-press;
return 0;
}
Works with starting from C++11, using experimental filesystem, and C++14-C++17 as well using official filesystem.
application.h:
#pragma once
//
// https://en.cppreference.com/w/User:D41D8CD98F/feature_testing_macros
//
#ifdef __cpp_lib_filesystem
#include <filesystem>
#else
#include <experimental/filesystem>
namespace std {
namespace filesystem = experimental::filesystem;
}
#endif
std::filesystem::path getexepath();
application.cpp:
#include "application.h"
#ifdef _WIN32
#include <windows.h> //GetModuleFileNameW
#else
#include <limits.h>
#include <unistd.h> //readlink
#endif
std::filesystem::path getexepath()
{
#ifdef _WIN32
wchar_t path[MAX_PATH] = { 0 };
GetModuleFileNameW(NULL, path, MAX_PATH);
return path;
#else
char result[PATH_MAX];
ssize_t count = readlink("/proc/self/exe", result, PATH_MAX);
return std::string(result, (count > 0) ? count : 0);
#endif
}
For relative paths, here's what I did. I am aware of the age of this question, I simply want to contribute a simpler answer that works in the majority of cases:
Say you have a path like this:
"path/to/file/folder"
For some reason, Linux-built executables made in eclipse work fine with this. However, windows gets very confused if given a path like this to work with!
As stated above there are several ways to get the current path to the executable, but the easiest way I find works a charm in the majority of cases is appending this to the FRONT of your path:
"./path/to/file/folder"
Just adding "./" should get you sorted! :) Then you can start loading from whatever directory you wish, so long as it is with the executable itself.
EDIT: This won't work if you try to launch the executable from code::blocks if that's the development environment being used, as for some reason, code::blocks doesn't load stuff right... :D
EDIT2: Some new things I have found is that if you specify a static path like this one in your code (Assuming Example.data is something you need to load):
"resources/Example.data"
If you then launch your app from the actual directory (or in Windows, you make a shortcut, and set the working dir to your app dir) then it will work like that.
Keep this in mind when debugging issues related to missing resource/file paths. (Especially in IDEs that set the wrong working dir when launching a build exe from the IDE)
A library solution (although I know this was not asked for).
If you happen to use Qt:
QCoreApplication::applicationDirPath()
Path to the current .exe
#include <Windows.h>
std::wstring getexepathW()
{
wchar_t result[MAX_PATH];
return std::wstring(result, GetModuleFileNameW(NULL, result, MAX_PATH));
}
std::wcout << getexepathW() << std::endl;
// -------- OR --------
std::string getexepathA()
{
char result[MAX_PATH];
return std::string(result, GetModuleFileNameA(NULL, result, MAX_PATH));
}
std::cout << getexepathA() << std::endl;
This question was asked 15 years ago, so the existing answers are now incorrect. If you're using C++17 or greater, the solution is very straightforward today:
#include <filesystem>
std::cout << std::filesystem::current_path();
See cppreference.com for more information.
On POSIX platforms, you can use getcwd().
On Windows, you may use _getcwd(), as use of getcwd() has been deprecated.
For standard libraries, if Boost were standard enough for you, I would have suggested Boost::filesystem, but they seem to have removed path normalization from the proposal. You may have to wait until TR2 becomes readily available for a fully standard solution.
Boost Filesystem's initial_path() behaves like POSIX's getcwd(), and neither does what you want by itself, but appending argv[0] to either of them should do it.
You may note that the result is not always pretty--you may get things like /foo/bar/../../baz/a.out or /foo/bar//baz/a.out, but I believe that it always results in a valid path which names the executable (note that consecutive slashes in a path are collapsed to one).
I previously wrote a solution using envp (the third argument to main() which worked on Linux but didn't seem workable on Windows, so I'm essentially recommending the same solution as someone else did previously, but with the additional explanation of why it is actually correct even if the results are not pretty.
As Minok mentioned, there is no such functionality specified ini C standard or C++ standard. This is considered to be purely OS-specific feature and it is specified in POSIX standard, for example.
Thorsten79 has given good suggestion, it is Boost.Filesystem library. However, it may be inconvenient in case you don't want to have any link-time dependencies in binary form for your program.
A good alternative I would recommend is collection of 100% headers-only STLSoft C++ Libraries Matthew Wilson (author of must-read books about C++). There is portable facade PlatformSTL gives access to system-specific API: WinSTL for Windows and UnixSTL on Unix, so it is portable solution. All the system-specific elements are specified with use of traits and policies, so it is extensible framework. There is filesystem library provided, of course.
The linux bash command
which progname will report a path to program.
Even if one could issue the which command from within your program and direct the output to a tmp file and the program
subsequently reads that tmp file, it will not tell you if that program is the one executing. It only tells you where a program having that name is located.
What is required is to obtain your process id number, and to parse out the path to the name
In my program I want to know if the program was
executed from the user's bin directory or from another in the path
or from /usr/bin. /usr/bin would contain the supported version.
My feeling is that in Linux there is the one solution that is portable.
Use realpath() in stdlib.h like this:
char *working_dir_path = realpath(".", NULL);
The following worked well for me on macOS 10.15.7
brew install boost
main.cpp
#include <iostream>
#include <boost/filesystem.hpp>
int main(int argc, char* argv[]){
boost::filesystem::path p{argv[0]};
p = absolute(p).parent_path();
std::cout << p << std::endl;
return 0;
}
Compiling
g++ -Wall -std=c++11 -l boost_filesystem main.cpp

Displaying unicode string using opengl, qt and freetype

I want to display text in OGL using FTGL(wrapper for FreeType2) in Qt. I have problem with unicode->FTGL must have charcode of actually rendering char, to get glyph from truetype font, which is problematic when this char is for example one of: 'Zażółć gęślą jaźń'.
Do you have any ideas, why this code:
const unsigned char *string=(const unsigned char*)"POCZUJ GĘŚLĄ JAŹŃ";
// for multibyte - we can't rely on sizeof(T) == character
FTUnicodeStringItr<T> ustr(string);
for(int i = 0; (len < 0 && *ustr) || (len >= 0 && i < len); i++)
{
unsigned int thisChar = *ustr++;
unsigned int nextChar = *ustr;
if(CheckGlyph(thisChar))
{
position += glyphList->Render(thisChar, nextChar,
position, renderMode);
}
}
works in Visual, but in Qt doesn't(it doesn't get proper charcodes, so it displays brackets)?
FTUnicodeStringItr template looks like this: http://www.nopaste.pl/11xt
Thanks.
The problem you're running into is, that C/C++ don't really support Unicode/wide characters in the source code. To be done properly you'd have to specify unicode characters either by \uXXXX escape sequences (if the compiler supports these), or by \xXX\xXX sequences building the code points from scratch. Visual C++ has wide character support (for the simple reason that all string manipulation in Windows is done in wide characters – don't confuse that with Unicode code points!).
I suggest you do the following: Qt has internationalization support built in. It boils down to define strings through the tr(...) helper function/macro with default language, i.e. english strings. Qt Linguist can then is used to create substitution rules, that are applied through the usage of tr(...) and does this with full Unicode support.

Getting values from pro files in Qt

I am using Qt 4.5 in Windows XP. My pro file has the variable VERSION = 1.0. Now i need to read this variable and get its value (1.0) from the source code. So that I don't have to maintain another variable for version inside my source code. I just read from the pro file and update it. So that the value remains consistent all over my project. Is it possible? Any pointers regarding this are welcome..
Use somethings like this:
DEFINES += VERSION=\\\"$$VERSION\\\"
This will define a macro that you can use in C source code. Get rid of the backslashes and quotes if you want a number, not a string.
I'll elaborate on this a bit.
In the YourApp.pro:
VERSION = 0.0.0.1
DEFINES += APP_VERSION=\\\"$$VERSION\\\"
In the main.cpp:
#include <QApplication>
QCoreApplication::setApplicationVersion(QString(APP_VERSION));
Wherever else in your sources, e.g. in the imaginary controller.cpp:
#include <QApplication>
QString yourAppVersion = QCoreApplication::applicationVersion();
somehow, when I tried qDebug() << QString(APP_VERSION); in a class.cpp not in main.cpp. has an error "C2065" APP_VERSION: undeclared identifier". but when I tried in main.cpp that worked.

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