Question

i have a question about a behaviour i don’t quite understand:

i have two variations of c++ code:

CreateThread( NULL, 0, ( LPTHREAD_START_ROUTINE ) clientThread, ( LPVOID ) connectionSocket, 0, NULL ); 

thread:

Client a;
a.clientsocket = connectionSocket;
a.testText()
a.sendSocket();

works just fine (sendSocket sends some test data to the socket).

However if i do

Client a;
a.clientsocket = connectionSocket;
CreateThread( NULL, 0, ( LPTHREAD_START_ROUTINE ) clientThread, ( LPVOID ) &a, 0, NULL );

and use
thread:

a.testText();
a.sendSocket();

only testText() works.

I am a bit confused why that is. I am a hobbyist on C++ though 🙂

edit:

added the Client class:

class Client
{
public:
    SOCKET clientsocket;

    Client()
{
}
~Client(){}
void displayMessage()
{
        std::cout << "test message client class" << std::endl;
}
int sendSocket()
{
    char *sendbuf = "CLIENT TEST";
    send(clientsocket, sendbuf, (int)strlen(sendbuf),0);
    closesocket(clientsocket);
    return 0;

}
};

Answer 1

Anon is might be on the right track that something goes out of scope, but I think that it’s the connectionSocket. However, you would have to provide more details on what you mean when you say that a.sendSocket() doesn’t work. Does the application crash? Do you catch an exception? Does the application continue to work, but the sendSocket() call didn’t result in actually sending something? What’s the actual problem?