Signals- Slots; emit one signal from one Form to multiple forms + mainwindow

[malone]

Thank you for your contribution,

I agree with Lesiok. You need to show the -complete code- not just the part you think is important.

My guess is that in every one of the signal / slot connections you are making, you are using a different instance of your "mInterface" class. I say this because in each of the connect() statements, it looks like you are using the address of a member variable (&interface) instead of a pointer. That tells me you are probably creating that variable on the stack during the construction of your forms and are not passing in the address of the single mInterface instance that is the one receiving the data. Only the first instance created does anything, because after it has been bound to the read socket, the other calls to bind() fail (but you don't bother to check to see if the bind() was successful...).

I think you are right. When I started the program found that the constructor of the class "mInterface" was called 3 times so 3 different instance of mInterface. once by calling the class Mainwindow + once by calling the class Readform and once by calling the class Form2. When i try with pointer by it is the same. I declared a pointer of mInterface in mainwindow, form2 and readForm for signals/slots-connection but nothing else happening only the same result.
How can i do that(to declare only one instance of mInterface )? can you give me a example?
thanks.

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Added after 1 8 minutes:

As I guessed:

class ReadForm has a member variable of type mInterface.
class Form2 has a member variable of type mInterface.
class MainWindow has a member variable of type mInterface.

When constructed, these become three completely independent instances of the mInterface class. Only one of them (whichever is constructed first - probably the one in the MainWindow instance constructed in main.cpp) will be successfully be bound to the socket and receive packets. For the other two, the call to bind() will fail because another instance got there first to bind the socket.

You need to rethink your design and consider how a single instance of a class can be shared among multiple other class instances. It isn't hard - I gave you a hint in my previous answer.

it runs very well. Thank you very much for your help.