How can I convert this C# code to C++? Can you help me?

Question

1.00/5 (2 votes)

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Normally I work with c#. but i don't know c++. I'm trying to learn. Is there a C++ equivalent of this code I asked you for?
and what I want to do is: check if an app is open, if it is open give a message error and and if it is closed give a continue command

What I have tried:

C#

Process[] EngineApp = Process.GetProcessesByName("xengine");
if (EngineApp.Length == 0)
{
    RunApplication();
}
else
{
    MessageBox.Show("You cannot open the application more than once.", "Connection error",
    MessageBoxButtons.OK, MessageBoxIcon.Error);
    Application.Exit();
}

Posted 13-Nov-21 19:02pm

xXRunnerNice RN

Updated 14-Nov-21 9:51am

v2

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3 solutions

Solution 2

note: i haven't touched c++ for years.

An app that can only have a single instance at any one time is called a singleton.

C++ singleton example: [^]

Another example: [^]

note: you might wat to review the discussion here about C++ singleton: [^]

Posted 14-Nov-21 4:49am

BillWoodruff

Updated 14-Nov-21 4:58am

v3

Comments

Richard MacCutchan 14-Nov-21 10:53am

But you can still start more than one instance of the actual application.

BillWoodruff 14-Nov-21 10:58am

hi, we are talking about making an app behave like a singleton class here.

"What is a Singleton class in C++?
Singleton in C++

"Singleton is a creational design pattern, which ensures that only one object of its kind exists and provides a single point of access to it for any other code. ... You can't just use a class that depends on Singleton in some other context. You'll have to carry the Singleton class as well."

https://refactoring.guru/design-patterns/singleton/cpp/example

Richard MacCutchan 14-Nov-21 11:22am

No he is asking how to ensure only one execution of a specific application is running at any one time. And the only way to do that is to check the running application list, or use a mutex when the application starts.

You can run any number of copies of an application, even if it contains a singleton class within it.

BillWoodruff 14-Nov-21 19:58pm

i treasure these moments when i can see we are, temporarily, in different universes :)

"No he is asking how to ensure only one execution of a specific application is running at any one time."

uhhh ... that is what I said.

"You can run any number of copies of an application, even if it contains a singleton class within it."

The OP is talking about an application, not a class: i assume the OP is/has written the App, and the task is to enforce singleton behavior on one machine. Use of Mutex is one standard way to create a Singleton in a context where thread safety is critical.

It's been over 15 years since i touched C++, and i am not aware of current issues in creating Win apps.

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Richard MacCutchan · Accepted Answer · 2021-11-13T21:05:00

Solution 1

See Enumerating All Processes - Win32 apps | Microsoft Docs[^].

Posted 13-Nov-21 21:05pm

Richard MacCutchan

merano99 · Accepted Answer · 2021-11-14T09:51:00

Solution 3

What is the C version of "Processes.GetProcessesByName(PROCESSNAME)?

Posted 14-Nov-21 9:51am

merano99

Comments

xXRunnerNice RN 15-Nov-21 8:05am

mmmm