Multiple asynchronous QProcesses

[E106JZ]

I'm trying to run multiple QProcess at runtime (around 1-12) aynchronously so I create a vector of unique_ptr for each QProcess and connect them in a loop like this:

std::vector<std::unique_ptr<QProcess>> processes;
processes.resize(threads);
for (int i=0; i<threads; i++)
{
    processes[i] = std::make_unique<QProcess>();
}
...
for (int i=0; i<threads; i++)
{
	connect(processes[i].get(), &QProcess::readyReadStandardOutput, this, [&]()
	{
		QByteArray readStdOut = processes[i]->readAllStandardOutput();
	});
}

However when I actually start my processes and receive data, I always get a segmentation fault because the index i is always equal to threads when data is received. Why does this happen and how do I fix this?

Thanks

[mrjj]

Hi
You capture i by reference so it will always point to the last values and not the value it had at that moment.

Try
....[&processes, i ](){};
or
....[&, i ](){};

so we capture process by ref and then i by value.

[E106JZ]

Thanks :)