Sign in to follow this  

Passing vector to a new thread

Recommended Posts

Hi Guys,

I am trying to work out how I can access a vector of structs from a new thread.

The creation is of the vector is done like so;

[code]void CoreNetwork::registerData(int nStructureType,void *pStructure,int nStructureSize)

But, I cant figure out how to iterate this data from another thread made with CreateThread().

Any help would be awesome. :cool:

Share this post

Link to post
Share on other sites
If you are referring to the [url=""]Win32 API CreateThread() function[/url], then you can use the fourth parameter [b]lpParameter[/b] to pass in arbitrary data into the thread as a pointer to void. This is a far more preferrable way than using global variables to pass data to a new thread.

Since you can only pass in a pointer to a single object, you have to group the data to a single struct if you need to pass in multiple variables. What you can do is create something like
struct ThreadCreationParameters
std::vector<int> myIntArray;
int someOtherData;
std::string someMoreData;

void StartThread()
ThreadCreationParameters *params = new ThreadCreationParameters;
// Populate contents of params here.
CreateThread(..., params, ...);

ThreadCreationParameters *params = reinterpret_cast<ThreadCreationParameters *>(param);
// Now can access parameters with params->xxx

// Remember to delete params after we are done.
delete params;

Note that it is important that you dynamically allocate the ThreadCreationParameters structure instead of placing it into the stack, since after exiting StartThread(), the stack would be cleared, and MyThreadMain would be accessing freed memory.

Also, remember that any variables you pass in ThreadCreationParameters by pointer or by reference need to be appropriately guarded with a synchronization primitive if both threads will be accessing the data.

Share this post

Link to post
Share on other sites
Awesome, I have been playing with your example and I get what is happening here :cool:

I'll apply it to my app and see how I go.

Thanks again for your help ;)

I have just translated this to suit my app and it looks like it is exactly what I need. Thanks again, bro! :cool:

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this