Atomic operations and Thread safe code

[blackstreetcat]

consider this code :

int i; //gobal var

Thread1:
i=some value;

Thread2:
if (i==2) dosomething();
else dosomethingelse();

I want to write it to be thread safe without using synchronization
objects.

my questions are:

1) is an assignment operation of an int atomic in c/c++?
if so will thaat code work?

volatile int i;

int getI()
{ return i;//assignment is atomic so assignment to return
value will be atomic also
}

void setI(int somevalue)
{
i=somevalue;//assignment atomic
}

Thread1:
setI(somevalue);

Thread2:
if (getI()==2) dosomething();
else dosomethingelse();


2) what operations in c are atomic?
are mailslots pipes etc operations atomic/threadsafe ?


thanks.

Katy.