gcc optimization? bug? and its practial implication to project

Question

My questions are divided into three parts

Question 1
Consider the below code,

#include 
using namespace std;

i         


        

Answer 1

Q1: Perhaps, the number is indeed positive in a 64bit implementation? Who knows? Before debugging the code I'd just printf("%d", i+v);

Q2: The parentheses are only there to tell the compiler how to parse an expression. This is usually done in the form of a tree, so the optimizer does not see any parentheses at all. And it is free to transform the expression.

Q3: That's why, as c/c++ programmer, you must not write code that assumes particular properties of the underlying hardware, such as, for example, that an int is a 32 bit quantity in two's complement form.