How to start other .exe and return value ?

[Taz742]

How to start other .exe and return value ?
Is it possible?

[jsulm]

@Taz742 http://doc.qt.io/qt-5/qprocess.html

[Taz742]

@jsulm
Yes I know how to run another program, but how do I get value from it?
Maybe you give me the right direction

[Taz742]

Let's assume that we are going to perform the operation that can be accomplished or not. I want to understand that.
For small instance, I send a number to another exe and give it back if this number is less than 100.

[J.Hilk]

@Taz742

if you want to keep it simple:

this Signal and this function most likly.

alternatively, QSharedMemory, TCP/UDP ...

[Taz742]

@J.Hilk
If my process is run .exe program that has a form we can do emit true or false or QVector ... QList...?
I can not understand how I could do that.

[jsulm]

@Taz742 Please read documentation, everything is there.
See http://doc.qt.io/qt-5/qiodevice.html#readyRead, http://doc.qt.io/qt-5/qiodevice.html#write-2, http://doc.qt.io/qt-5/qprocess.html#readAllStandardOutput
There is even an example showing how to do it:

QProcess gzip;
gzip.start("gzip", QStringList() << "-c");
if (!gzip.waitForStarted())
    return false;

gzip.write("Qt rocks!");
gzip.closeWriteChannel();

if (!gzip.waitForFinished())
    return false;

QByteArray result = gzip.readAll();

[jsulm]

@Taz742 said in How to start other .exe and return value ?:

If my process is run .exe program that has a form we can do emit true or false or QVector ... QList...?
I can not understand how I could do that.

You either use stdout/stdin like shown in my post above. Or you use some kind of IPC (Inter Process Communication). For example shared memory, DBus, ...
See http://doc.qt.io/qt-5/qtcore-ipc-sharedmemory-example.html for shared memory.

[VRonin]

I think the main question here is: how does your external application returns the data?

• does it exit with a different code for each possible result (it would be unsual but I'm not ruling it out)?
• does it print to standard output (the console) the answer? if so in what format?
• does it communicate in any other way (shared memory,DBus,TCP,Local Socket, HTTP, FTP, etc)?