C++ Quiz starts here...>

DanielKO

The default comma operator is just a sequence operator, that does absolutely nothing. If you are going to count it as an "implicit function", so does the add (+), increment (++), multiply (*), etc. :)

I don't think new and delete count as "implicit"; I consider them built-in, just like the operators on primitive types. In fact, the compiler won't generate any code, it will just call the implementation provided by the standard library - that's why you can replace them through <new> (as the linkage of the standard library happens after the symbols were resolved); so new and delete are as implicit as malloc and free.

BTW, right after posting, I checked my copy of the standard to make sure, and it also lists the implicit functions the same way I did. So anything beyond this is a matter of interpretation of what "THE SPECIAL FUNCTIONS A C++ COMPILER CAN CREATE IMPLICITY" means.

Hurkyl

If x and y are objects of your class, you cannot write x + y unless you explicitly define operator+, and similarly for the other functions you mentioned. On the other hand, you can write x, y without providing an explicit definition of operator,.

DanielKO

Because the plain comma operator is exactly the same present in the C language: it does nothing (other than separating two expressions by a sequence point, and evaluating to the second expression). Maybe you would like to consider the (void) conversion operator as "implicitly created by the compiler"? After all, you can write (void)x; without providing an explicit definition.

You are considering a C language construct as an "implicitly created function".