Author Archives: dmitriano

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19
12
22
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“One Edit Apart” task on Yandex interview

Posted by | C++ |

The task is to write one_edit_apart function that determines is it possible to make two given strings equal by replacing, adding or removing one symbol. The equal strings are considered to be equal, for example:

one_edit_apart("cat", "at") == true
one_edit_apart("cat", "cats") == true
one_edit_apart("cat", "cast") == true
one_edit_apart("cast", "cats") == false
one_edit_apart("cat", "cut") == true
one_edit_apart("cat", "dog") == false

The task is trivial, but Yandex interviewers require all the calculation to be done exactly in their inline editor without debugging and compiling and they do not accept the solution until it works for all possible input. The obvious solution is to truncate equal heads and equal tails and check if the lengths of remaining strings are not greater than 1, but if you forgot to handle the case when heads and tails intersect (with “a” and “aa”, for example) they will say “ooops…., you did a newbie mistake that 1-st year students usually do” and if this all takes more than 40 minutes you fail to pass the test. Below I provided the source code they are most likely to accept:

(more…)
11
12
22
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QT has Translation Rules for Plurals

Posted by | QT |

For example, there is the following content in qt-everywhere-src-6.4.1\qttranslations\translations\linguist_ru.ts:

<message numerus="yes">
    <source>Dropped %n message(s) which had no ID.</source>
    <translation>
        <numerusform>Удалено %n сообщение, у которого не было ID.</numerusform>
        <numerusform>Удалено %n сообщения, у которых не было ID.</numerusform>
        <numerusform>Удалено %n сообщений, у которых не было ID.</numerusform>
    </translation>
</message>
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11
12
22
 2 Comments

Building QT6.4.1 for Android on Windows

Posted by | QT |

Build QT6.4.1 for Windows and then build it for Android as follows:

set MY_DRIVE=D:

cd %MY_DRIVE%\dev\build\qta
%MY_DRIVE%
     
set "CMAKE_ROOT=%MY_DRIVE%\dev\tools\cmake-3.24.2-windows-x86_64\bin"
set "NINJA_ROOT=%MY_DRIVE%\dev\tools\ninja-win"
set "PERL_ROOT=%MY_DRIVE%\dev\tools\Strawberry\perl\bin"
set "MINGW_ROOT=%MY_DRIVE%\dev\tools\x86_64-12.2.0-release-win32-seh-rt_v10-rev0\mingw64\bin"
set "PYTHON_ROOT=%MY_DRIVE%\dev\tools\Python35"
set "JDK_ROOT=C:\Program Files\Android\Android Studio\jre\bin"
             
set PATH=C:\WINDOWS\system32;C:\WINDOWS
set PATH=%CMAKE_ROOT%;%PATH%
set PATH=%NINJA_ROOT%;%PATH%
set PATH=%MINGW_ROOT%;%PATH%
set PATH=%PERL_ROOT%;%PATH%
set PATH=%PYTHON_ROOT%;%PATH%
set PATH=%JDK_ROOT%;%PATH%
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10
12
22
 3 Comments

Building QT6.4.1 for Windows

Posted by | QT |

Extract QT sources:

cd /d/dev/repos
tar -xf ../distrib/qt-everywhere-src-6.4.1.tar.xz

Configure QT as follows:

"C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Auxiliary\Build\vcvarsall.bat" amd64

set MY_DRIVE=D:

%MY_DRIVE%

cd %MY_DRIVE%\dev\build\qt
   
set "CMAKE_ROOT=%MY_DRIVE%\dev\tools\cmake-3.24.2-windows-x86_64\bin"
set "NINJA_ROOT=%MY_DRIVE%\dev\tools\ninja-win"
set "PERL_ROOT=%MY_DRIVE%\dev\tools\Strawberry\perl\bin"
       
set PATH=%CMAKE_ROOT%;%PATH%
set PATH=%NINJA_ROOT%;%PATH%
set PATH=%PERL_ROOT%;%PATH%
set PATH=%MY_DRIVE%\dev\tools\Python35;%PATH%
(more…)
10
12
22
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Translation of standard buttons text on Android in QT6

Posted by | QT |

Found the following code in qt-everywhere-src-6.4.0\qtbase\src\plugins\platforms\android\qandroidplatformtheme.cpp:

QString QAndroidPlatformTheme::standardButtonText(int button) const
{
    switch (button) {
    case QPlatformDialogHelper::Yes:
        return QCoreApplication::translate("QAndroidPlatformTheme", "Yes");
    case QPlatformDialogHelper::YesToAll:
        return QCoreApplication::translate("QAndroidPlatformTheme", "Yes to All");
    case QPlatformDialogHelper::No:
        return QCoreApplication::translate("QAndroidPlatformTheme", "No");
    case QPlatformDialogHelper::NoToAll:
        return QCoreApplication::translate("QAndroidPlatformTheme", "No to All");
    }
    return QPlatformTheme::standardButtonText(button);
}
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17
11
22
 1 Comment

Key knowledge about forwarding references in C++

Posted by | C++ |

The compiler deduces U as std::string& or as std::string depending on value category of the argument:

template <class U>
void f(U&& s)
{
    static_assert(std::is_same_v<U, const std::string&>);

    std::cout << std::forward<U>(s) << std::endl;
}

int main()
{
    const std::string& s = "abc";

    f(s);

    return 0;
}
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02
11
22
 2 Comments

Creating Windows Application Icon on Ubuntu 22.04

Posted by | Ubuntu, Windows |

Install magick tool:

sudo apt update
sudo apt install imagemagick

Copy *.png files to a folder, for example:

win16x16.png
win32x32.png
win48x48.png
win64x64.png

and run the following command:

convert *.png winapp.ico
31
10
22
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QDebug can’t be used from a destructor of a static object

Posted by | QT |

We can’t do this in QT:

class Global
{
public:

    ~Global()
    {
        qDebug() << "Global destructor.";
    }
};

Global g;
(more…)
29
10
22
 2 Comments

QML Application Style

Posted by | QML, QT |

There was qtquickcontrols2.conf in the root directory of my app sources with the following content:

; This file can be edited to change the style of the application
; See Styling Qt Quick Controls 2 in the documentation for details:
; https://doc.qt.io/qt-6/qtquickcontrols2-styles.html

[Controls]
;Style=Default
;Style=Universal
;Style=Material
Style=Fusion
;Style=iOS

[Universal]
Theme=Light
Accent=Steel

[Material]
;Theme=Light
Theme=Dark
;Accent=BlueGrey
;Primary=BlueGray
(more…)
23
10
22
 1 Comment

QT6 multimedia module crashes on iOS

Posted by | iOS, QT |

After several hours of playing sounds my iOS app crashes and the QT Creator displays the following stack trace:

1 caulk::thread::join() (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/caulk.framework/caulk 0x7fff49a06293
2 std::__shared_ptr_emplace<AURemoteIO::IOThread, std::allocator<AURemoteIO::IOThread>>::__on_zero_shared() (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff438a7469
3 AURemoteIO::Stop() (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff438a58d3
4 ausdk::AUMethodStop(void *) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff438f3529
5 QDarwinAudioSink::audioDeviceStop() qdarwinaudiosink.mm 619 0x10ffa7afd
6 QDarwinAudioSink::audioDeviceIdle() qdarwinaudiosink.mm 629 0x10ffa7b68
7 QDarwinAudioSink::renderCallback(void *, unsigned int *, AudioTimeStamp const *, unsigned int, unsigned int, AudioBufferList *) qdarwinaudiosink.mm 446 0x10ffa7ab7
8 ausdk::AUInputElement::PullInput(unsigned int&, AudioTimeStamp const&, unsigned int, unsigned int) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff438f12d2
9 AUInputFormatConverter2::InputProc(OpaqueAudioConverter *, unsigned int *, AudioBufferList *, AudioStreamPacketDescription * *, void *) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff4382cf27
10 acv1::AudioConverterChain::CallInputProc(unsigned int) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore 0x7fff30323840
11 acv1::AudioConverterChain::FillBufferFromInputProc(unsigned int *, CADeprecated::CABufferList *) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore 0x7fff3032467f
12 acv1::BufferedAudioConverter::GetInputBytes(unsigned int, unsigned int&, CADeprecated::CABufferList const *&) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore 0x7fff3045c7bd
13 acv1::CBRConverter::RenderOutput(CADeprecated::CABufferList *, unsigned int, unsigned int&, AudioStreamPacketDescription *) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore 0x7fff303091bc
14 acv1::BufferedAudioConverter::FillBuffer(unsigned int&, AudioBufferList&, AudioStreamPacketDescription *) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore 0x7fff3045c589
15 acv1::AudioConverterChain::RenderOutput(CADeprecated::CABufferList *, unsigned int, unsigned int&, AudioStreamPacketDescription *) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore 0x7fff303235bb
16 acv1::BufferedAudioConverter::FillBuffer(unsigned int&, AudioBufferList&, AudioStreamPacketDescription *) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore 0x7fff3045c589
17 acv1::_AudioConverterFillComplexBuffer(OpaqueAudioConverter *, int ( *)(OpaqueAudioConverter *, unsigned int *, AudioBufferList *, AudioStreamPacketDescription * *, void *), void *, unsigned int *, AudioBufferList *, AudioStreamPacketDescription *, AudioStreamPacketDependencyInfo *) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore 0x7fff30491df6
18 AudioConverterFillComplexBuffer (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/AudioToolboxCore.framework/AudioToolboxCore 0x7fff303a3680
19 AUConverterBase::RenderBus(unsigned int&, AudioTimeStamp const&, unsigned int, unsigned int) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff4382b617
20 AURemoteIO::RenderBus(unsigned int&, AudioTimeStamp const&, unsigned int, unsigned int) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff438a4317
21 ausdk::AUBase::DoRender(unsigned int&, AudioTimeStamp const&, unsigned int, unsigned int, AudioBufferList&) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff438f06a9
22 AURemoteIO::PerformIO(unsigned int, unsigned int, unsigned int, AudioTimeStamp const&, AudioTimeStamp const&, AudioBufferList const *, AudioBufferList *, unsigned int&) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff438af7df
23 _XPerformIO (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff438e9817
24 mshMIGPerform (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/usr/lib/libAudioToolboxUtility.dylib 0x7fff2e30936a
25 MSHMIGDispatchMessage (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/usr/lib/libAudioToolboxUtility.dylib 0x7fff2e309759
26 void * caulk::thread_proxy<std::tuple<caulk::thread::attributes, AURemoteIO::IOThread::IOThread(AURemoteIO&, caulk::thread::attributes const&, caulk::mach::os_workgroup const&)::'lambda'(), std::tuple<>>>(void *) (x86_64) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/System/Library/Frameworks/AudioToolbox.framework/libEmbeddedSystemAUs.dylib 0x7fff438a7200
27 _pthread_start (x86_64) /usr/lib/system/libsystem_pthread.dylib 0x7fff6da2b8fc
28 thread_start (x86_64) /usr/lib/system/libsystem_pthread.dylib 0x7fff6da27443
(more…)
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