Quote:Original post by LessBread
That would make the pointer point to the address 0x00000002. Accessing that address would probably throw an exception.

You're absolutely right, but using the method you posted would also cause hard to debug errors if the class/function the value is passed to uses that value later on, after the original "__int32 var1" fell out of scope.

After looking closer at the CreateThread() the OP mentioned, what he should be doing is exactly what you said, except that he should just pass the address of var1 as the parameter, instead of copying that address to var2. I'm sure there's a good reason CreateThread was designed that way, but I have no idea what it is.

Quote:Original post by Prgrmr@wrk

Quote:Original post by LessBread
That would make the pointer point to the address 0x00000002. Accessing that address would probably throw an exception.

You're absolutely right, but using the method you posted would also cause hard to debug errors if the class/function the value is passed to uses that value later on, after the original "__int32 var1" fell out of scope.

After looking closer at the CreateThread() the OP mentioned, what he should be doing is exactly what you said, except that he should just pass the address of var1 as the parameter, instead of copying that address to var2. I'm sure there's a good reason CreateThread was designed that way, but I have no idea what it is.

I didn't understand the problem when I posted that snippet. It was when I saw your "left side hack" (for lack of a better description) that I saw what the OP was going after. It seems to me that if he just wants to pass an integer value to CreateThread the solution is to simply cast the integer variable as a void pointer, pass it in and then inside the thread function recast it to a local integer variable. It seems to me that falling out of scope is not an issue if the parameter is treated as an "in" rather than an "in/out". Thinking about this a bit more, it would seem that the argument passed to the thread function resides on that thread's stack so it should be accessible until the thread function returns.

int var = 2;

CreateThread(..., (void*)var, ...);

int ThreadFunk(void *param)
{
int var = (int)param;
...
}