Re: std::vector anomally
On Mon, 17 Dec 2007 01:11:47 -0200, "John Keenan"
<john.removeme.keenan@optimapowerware.com> wrote:
"Doug Harrison [MVP]" <dsh@mvps.org> wrote
Aside: Did you know these declare the same function?
void f(int);
void f(const int);
No I was not aware of that. In VS6 the following only give compiler errors
where indicated. Am I misreading something here?
John
void i1( int i_ );
void i2( const int i_ );
class Xxx{
o o o
void i1( int i_ ) const;
void i2( const int i_ ) const;
};
void i1( int i_ ) {
int j = i_;
i_ = 3;
}
void i2( const int i_ ) {
int j = i_;
i_ = 3; //error C2166: l-value specifies const object
}
void Xxx::i1( int i_ ) const {
int j = i_;
i_ = 3;
}
void Xxx::i2( const int i_ ) const {
int j = i_;
i_ = 3; //error C2166: l-value specifies const object
}
The compiler doesn't allow you to modify const objects; that's the whole
point, right? Nevertheless, what I said is correct, but you clipped the
part which sort of explained why:
From the user's perspective, the "const" is noise, and header files should
use the first one. You can use the second one when you define the function,
but in the real world, this is typically not done as much as it should be.
The easiest way to convince yourself that the declarations I gave represent
the same function is to try to compile the following:
void f(int)
{
}
void f(const int)
{
}
The so-called "top-level const" is ignored for the purpose of
differentiating the function types, so the compiler will see the second "f"
as an attempt to redefine the first one.
--
Doug Harrison
Visual C++ MVP