Remedial C++ Question

[clutz123]

Hello all, I have a very simple question regarding reading some code:

If the code is:

--
class ClassName {
public:
ClassName (int x = 0) : _variable1(at),
_variable2(2) {}


private:
int _variable1;
int _variable2;
};
--

Is the the same as creating a constructor with the statements

...
public:
ClassName (int x = 0)
{
_variable1 = x;
_variable2 = 2;
}
...
?

Thanks!

 

[Markbnj]

I think perhaps you made a typo. The use of 'at' doesn't mean anything in the member initialization list.

class ClassName {
public:
ClassName (int x = 0) : _variable1(x),
_variable2(2) {}


private:
int _variable1;
int _variable2;
};

Is the same as...

ClassName (int x = 0)
{
_variable1 = x;
_variable2 = 2;
}

Except that the first form, using the member initialization list, is preferred because the body of the constructor does not execute until all base classes have been constructed. That may not matter at all, but you usually want to initialize a variable as close to when its memory is allocated as possible.