why Visual Studio can not optimize the initialization code?

[George2]

Hello everyone,


Why Visual Studio compiler can not optimize in this case? I think this case is almost the same as sample 1, why compiler can optimize sample 1 but can not optimze sample 2?

(sample 2, http://msdn2.microsoft .com/en-us/library/ms364057(vs.80) .aspx)

#include <stdio.h>
class A {
  public:
    A() {printf ("A: I am in constructor\n");i = 1;}
    ~A() { printf ("A: I am in destructor\n"); i = 0;}
    A(const A& a) {printf ("A: I am in copy constructor\n"); i = a.i;}
    int i, x, w;
};
 class B {
  public:
    A a;
    B()  { printf ("B: I am in constructor\n");}
    ~B() { printf ("B: I am in destructor\n");}
    B(const B& b) { printf ("B: I am in copy constructor\n");}
};
A MyMethod()
{
    B* b = new B();
    A a = b->a;
    delete b;
    return (a);
}
int main()
{
    A a;
    a = MyMethod();
}
 

thanks in advance,
George

[weaknessforcats]

Optimization is an advanced topic. You need no be concerned with this until after your C++ program has been coded and debugged. And maybe not even then.

I have been using C++ for 17 years and have not yet needed to optimize. My applications just didn't warrant it.

I would post this question again when you have about 5 yrs C++ experience.

[George2]

Hi weaknessforcats ,


I have programmed with C++ for more than 5 years, including the time in school. Any ideas for the question. :-)

Optimization is an advanced topic. You need no be concerned with this until after your C++ program has been coded and debugged. And maybe not even then.

I have been using C++ for 17 years and have not yet needed to optimize. My applications just didn't warrant it.

I would post this question again when you have about 5 yrs C++ experience.

regards,
George

[weaknessforcats]

In that case, start here: http://msdn2.microsoft.com/en-us/lib...e8(VS.71).aspx.

[George2]

Thanks for your advice, weaknessforcats !

In that case, start here: http://msdn2.microsoft.com/en-us/lib...e8(VS.71).aspx.

regards,
George