You are lacking the installation of the the QtSvg library. Try to install them on your Ubuntu 13.10 in the following way:

    sudo apt-get install libqt5svg5*

Debian Stretch:

    sudo apt install libqt5svg5-dev

Fedora (courtesy of @robin-green):

    sudo dnf install qt5-qtsvg-devel

Because zsh complains to me about &quot;no matches found&quot; when using lpapp&#39;s answer, I would like to add here:
On Debian Systems one can get the required library for **release builds** via:

    sudo apt install libqt5svg5

and if one also wants to build a **debug build** one requires:

    sudo apt install libqt5svg5-dev

additionally.

For the longest time I thought asynchronous was synonymous to running something on a background thread, while synchronous meant on the main thread (blocking UI updates and interactions). I understand that not running on the main thread for expensive actions is because it doesn&#39;t allow UI actions to occur as the main thread is occupied, but why is synchronous troublesome?

However, it&#39;s since came to my attention that you can make asynchronous calls on the main thread, and synchronous calls on background threads.

I always hear people saying not to use expensive calls synchronously or on the main thread, as it will block the UI for the user. Are these two separate issues I should be making sure I don&#39;t do? What are the differences?

What&#39;s the difference between synchronous and asynchronous calls in Objective-C, versus multi-threading?

I have the following entry in my DB table

    eventName(varchar 100) -&gt; myEvent
    date(timestamp) -&gt; 2013-03-26 09:00:00

and I am trying to use the following query;

    SELECT * 
    FROM eventList 
    WHERE `date` BETWEEN UNIX_TIMESTAMP(1364256001) AND UNIX_TIMESTAMP(1364342399)

i.e between 2013-03-26 00:00:01 and 2013-03-26 23:59:59

but it is giving me 0 results.

I have tried expanding the date range with no luck and there are definitely results within the range.

any help is appreciated.

MYSQL query between two timestamps

Added QT += svg and I tried just QT += svg and greaterThan(QT_MAJOR_VERSION, 4): QT += svg to the .pro solution file and ran qmake from inside the QtCreator and got this error:

&gt; error: Unknown module(s) in QT: svg

Any ideas?

Unknown module(s) in QT: svg

Added QT += svg and I tried just QT += svg and greaterThan(QT_MAJOR_VERSION, 4): QT += svg to the .pro solution file and ran qmake from inside the QtCreator and got this error:
> error: Unknown module(s) in QT: svg
Any ideas?

In ObjC with GCD, there is a way of executing a lambda in any of the threads that spin an event loop. For example:

    dispatch_sync(dispatch_get_main_queue(), ^{ /* do sth */ });

or:

    dispatch_async(dispatch_get_main_queue(), ^{ /* do sth */ });

It executes something (equivalent to `[]{ /* do sth */ }` in C++) in the main thread&#39;s queue, either blocking or asynchronously.

How can I do the same in Qt?

From what I have read, I guess the solution would be somehow to send a signal to some object of the main thread. But what object? Just `QApplication::instance()`? (That is the only object living in the main thread at that point.) And what signal?

---

From the current answers and my current research, it really seems that I need some dummy object to sit in the main thread with some slot which just waits to get in some code to execute.

So, I decided to subclass `QApplication` to add that. My current code, which doesn&#39;t work (but maybe you can help):
    
    #include &lt;QApplication&gt;
    #include &lt;QThread&gt;
    #include &lt;QMetaMethod&gt;
    #include &lt;functional&gt;
    #include &lt;assert.h&gt;
    
    class App : public QApplication
    {
    	Q_OBJECT
    		
    public:
    	App();
    	
    signals:
    	
    public slots:
    	void genericExec(std::function&lt;void(void)&gt; func) {
    		func();
    	}
    
    private:
    	// cache this
    	QMetaMethod genericExec_method;
    public:
    	void invokeGenericExec(std::function&lt;void(void)&gt; func, Qt::ConnectionType connType) {
    		if(!genericExec_method) {
    			QByteArray normalizedSignature = QMetaObject::normalizedSignature(&quot;genericExec(std::function&lt;void(void)&gt;)&quot;);
    			int methodIndex = this-&gt;metaObject()-&gt;indexOfSlot(normalizedSignature);
    			assert(methodIndex &gt;= 0);
    			genericExec_method = this-&gt;metaObject()-&gt;method(methodIndex);
    		}
    		genericExec_method.invoke(this, connType, Q_ARG(std::function&lt;void(void)&gt;, func));
    	}
    	
    };
    
    static inline
    void execInMainThread_sync(std::function&lt;void(void)&gt; func) {
    	if(qApp-&gt;thread() == QThread::currentThread())
    		func();
    	else {
    		((App*) qApp)-&gt;invokeGenericExec(func, Qt::BlockingQueuedConnection);
    	}
    }
    
    static inline
    void execInMainThread_async(std::function&lt;void(void)&gt; func) {
    	((App*) qApp)-&gt;invokeGenericExec(func, Qt::QueuedConnection);
    }
    



How to execute a functor or a lambda in a given thread in Qt, GCD-style?

While debugging `C++` code in Qt creator I get the following error

    ptrace: Operation not permitted.
    
    Could not attach to the process. Make sure no other debugger traces this process.
    Check the settings of
    /proc/sys/kernel/yama/ptrace_scope
    For more details, see /etc/sysctl.d/10-ptrace.conf

Here a temporary solution is found: [Receiving error while trying to debug in QtProject][1]

 - temporary solution (won&#39;t survive a reboot):

     `echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope`


But it is difficult to run the same code in terminal every time when I start my PC to use Qt. 

    What is the permanent solution for this?

  [1]: https://askubuntu.com/questions/244336/receiving-error-while-trying-to-debug-in-qtproject


Qt Creator, ptrace: Operation not permitted. What is the permanent solution?

I am using Qt Designer, and I would like to move a couple of top-level widgets into a horizontal layout.

I have dragged a &quot;Horizontal Layout&quot; object into the form.  I am now attempting to drag the desired widgets into the layout.

Unfortunately, the new Horizontal Layout widget is infinitely thin:

![Infinitely Thin Layout][1]

... and I cannot drag my &quot;Import Progress&quot; label widget or my progress bar widget into the new horizontal layout widget.

Note that when I attempt to drag the desired widgets over the new horizontal layout widget, Qt Designer does not do anything useful for me in terms of expanding the drop region to make the horizontal widget available as a drop target.  So I&#39;m stuck.

How do I add widgets to an infinitely-thin layout widget in Qt Designer?


  [1]: http://i.stack.imgur.com/Tzhvk.jpg

Qt designer: How to add widget to a layout in the designer when the layout appears infinitely thin?

I use Python 3 and PyQt5. Here&#39;s my test PyQt5 program, focus on the last 2 lines:

    from PyQt5.QtCore import *
    from PyQt5.QtWidgets import *
    import sys

    class window(QWidget):
	def __init__(self,parent=None):
		super().__init__(parent)
		self.setWindowTitle(&#39;test&#39;)
		self.resize(250,200)

    app=QApplication(sys.argv)
    w=window()
    w.show()
    sys.exit(app.exec())
    #sys.exit(app.exec_())

I know `exec` is a language keyword in Python. But code on [Official PyQt5 Documentation][1] *(specifically the **Object Destruction on Exit** part)*. I see that example shows use of `app.exec()` which confuses me.

When I tested it on my machine. I found there is no any visible difference from my end. Both with and without `_` produces the same output in no time difference.

My question is:

 - Is there anything wrong going when I use `app.exec()`? like clashing with Python&#39;s internal `exec`? I suspect because both `exec`&#39;s are executing something.
 - If not, can I use both interchangeably?

  [1]: http://pyqt.sourceforge.net/Docs/PyQt5/pyqt4_differences.html#object-destruction-on-exit

Should I use `app.exec()` or `app.exec_()` in my PyQt application?

I wanted to know if there is a way to do a silent install of the Qt run installer on Ubuntu Server?  
I mean by-pass the options of the installer and do a default install?

Silent install Qt run installer on ubuntu server

NodeJS interpreter name(`node`) on Ubuntu has been renamed to `nodejs` because of a name conflict with another package. Here&#39;s what the readme. Debian says:

&gt;   The upstream name for the Node.js interpreter command is &quot;node&quot;.
&gt;   In Debian the interpreter command has been changed to &quot;nodejs&quot;.
&gt;
&gt;   This was done to prevent a namespace collision: other commands use
&gt;   the same name in their upstream, such as ax25-node from the &quot;node&quot;
&gt;   package.
&gt;
&gt;   Scripts calling Node.js as a shell command must be changed to instead
&gt;   use the &quot;nodejs&quot; command.

However, using nodejs mucks up installing packages using `npm`. Package installation fails with the following error:

&gt;     sh: 1: node: not found
&gt;     npm WARN This failure might be due to the use of legacy binary &quot;node&quot;
&gt;     npm WARN For further explanations, please read /usr/share/doc/nodejs/README.Debian

How do I make npm understand that nodejs is already installed on the system but the interpreter name is different?

Cannot install packages using node package manager in Ubuntu

I am facing an issue on ubuntu 12.04 as :

&gt; /usr/lib/ndk/android-ndk-r8c/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/as:
&gt; error while loading shared libraries: libz.so.1: cannot open shared
&gt; object file: No such file or directory

I tried 

    sudo apt-get install lib32z1

But it says 

&gt; Reading package lists... Done Building dependency tree        Reading
&gt; state information... Done lib32z1 is already the newest version. 0
&gt; upgraded, 0 newly installed, 0 to remove and 610 not upgraded.

Please suggest a solution.

libz.so.1: cannot open shared object file

Ubuntu typing &#39;php&#39; in terminal shows a lot of errors

I run `sudo pip install git-review`, and get the following messages:

&lt;!-- language: lang-none --&gt;

    Downloading/unpacking git-review
      Cannot fetch index base URL http://pypi.python.org/simple/
      Could not find any downloads that satisfy the requirement git-review
    No distributions at all found for git-review
    Storing complete log in /home/sai/.pip/pip.log

Does anyone has any idea about this?


pip connection failure: cannot fetch index base URL http://pypi.python.org/simple/

I am trying to install Jenkins on Ubuntu 13.10 and I am getting the above mentioned error when i try to run the following command:

    wget -q -O - http://pkg.jenkins-ci.org/debian/jenkins-ci.org.key | sudo apt-key add -

gpg: no valid OpenPGP data found

How do I know which version of Qt I am using? When I open Qt Creator it shows &quot;Welcome to Qt Creator 2.3&quot;. In the build setting, however, it shows Qt Version 4.7.1.

How to find Version of Qt?

I have seen references to all three of these applications on various parts of the Qt website but am completely unclear as to the exact differences between them and whether they are actually separate things or just different names for the same thing, or the name changed over time? Or is one no longer supported? What&#39;s the deal with these?


Qt Designer vs Qt Quick Designer vs Qt Creator?

Installed just the IDE on Windows 7.  I want to create a Plain C++ Project (Non-QT Project); however I get an error: **No valid kits found**.  When I click on Options-&gt;Kits, I see the *Desktop (default)* kit, and it shows no errors.  

Am I getting the error because I didn&#39;t install a Qt library?  If so, is there any way I can bypass downloading/installing that and just use the IDE?

QtCreator: No valid kits found

I just installed Qt 5.5 and am using Qt Creator for the first time on OS X.  When I first installed Qt, it gave me an error message &#39;Xcode 5 not installed&#39; which I thought was strange, (I have the Xcode 7 beta), but the install completed successfully anyways.

Now, when I start or open a project, I get the error:

&gt;Project ERROR: Xcode not set up properly. You may need to confirm the license agreement by running /usr/bin/xcodebuild.

When I run `/usr/bin/xcodebuild` in Terminal, I get the following:

&gt;xcode-select: error: tool &#39;xcodebuild&#39; requires Xcode, but active developer directory &#39;/Library/Developer/CommandLineTools&#39; is a command line tools instance

I&#39;m not sure what Xcode has to do with Qt Creator, unless it has something to do with accessing libraries for cross-platform compatibility, but is there a way to fix this issue?

Qt Creator - Project ERROR: Xcode not set up properly. You may need to confirm the license agreement by running /usr/bin/xcodebuild

I am using Ubuntu 14.04. I&#39;m trying to install a program which requires cmake. When I run `cmake src/` I get: 

    qmake: could not exec &#39;/usr/lib/x86_64-linux-gnu/qt4/bin/qmake&#39;: No such file or directory

What am I doing wrong?

cmake not working, could not exec qmake

I would like to know  *reasons for use `CMake` for particular project over `qmake` and vice versa*. 

Simply what are the pros and cons of both build systems? 

Content Type	Original Author	Original Content on Stackoverflow
Question	user3191398	View Question on Stackoverflow
Solution 1 - Qt	lpapp	View Answer on Stackoverflow
Solution 2 - Qt	user1338062	View Answer on Stackoverflow
Solution 3 - Qt	J. Wilde	View Answer on Stackoverflow

Unknown module(s) in QT: svg

Qt Problem Overview

Qt Solutions

Solution 1 - Qt

Solution 2 - Qt

Solution 3 - Qt

MYSQL query between two timestamps

What's the difference between synchronous and asynchronous calls in Objective-C, versus multi-threading?

Attributions