On 10 December 2014 at 13:09, Jonathan Wakely wrote: > On 10 December 2014 at 13:03, Graziano Servizi wrote: >> Hi, >> >> by pure chance, during a copy+paste editing operation of a source code, >> I ended up inadvertently with a code line like the following: >> >> int * x = int(); >> >> Well, this code HAD BEEN COMPILED by g++ 4.8.3, and I cannot figure out its >> meaning (from the compiler's point of view). > > int() creates an integer with value zero. > > In C++03 any integer expression with value zero is a valid null > pointer value, so you can do any of these: > > int* p1 = 0; > int* p2 = '\0'; > int* p3 = 1-1; I should have said any integer *constant* expression. The exact wording was: "A null pointer constant is an integral constant expression (5.19) prvalue of integer type that evaluates to zero or a prvalue of type std::nullptr_t." This was modified by http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#903 so that only integer literals are valid, so now int() and 1-1 are not valid null pointer constants.
