Quick Question On Constructors

[zb0S216C]

Can I call a member method in a constructor? Here's a quick example that shows what I mean if you don't already:

struct STRUCT
{
    STRUCT( void )
    {
        InitX( 7 );
    }
   
    int X;
    
    void InitX( const int Init )
    {
        X = Init;
    }
};

Much appreciated.

[Khaltazar]

class ClassName
{
    private:
        DataType VariableName;
    public:
        void Methods;
        ClassName();
        ~ClassName(){};
};

ClassName::ClassName()
{
    VariableName = Value;
}

I threw that together really quick.
A constructor can only set a variable to default values. I don't think it will work for methods.

[zb0S216C]

Thanks, Khaltazar. It makes sense that destructors can call member methods but constructors calling member methods didn't seem correct.

Thanks for clearing that up for me.

[jsmith]

A constructor can call any non-virtual method. However, keep in mind that assignment and initialization are two different things in C++. In OP's original example, a better way to do that would be:

struct S {
    S() : X( 7 ) {}
};

using an initializer list instead of an assignment.

[zb0S216C]

I do agree that assignment and initialization are two different things. So, S() : X( 7 ) is initialization not assignment?

[jsmith]

Yes. Assignment always uses an explicit equals sign.

[EDIT: But not all equals signs are assignments.]

[kooth]

I almost always add a private function named void Init() and I call it in every constructor and operator = . It makes initialization of many variables simple.

[jsmith]

Fortunately C++0x provides delgating constructors which obviate the need for such an Init method call in the constructor.
http://www2.research.att.com/~bs/C++0xFAQ.html#delegating-ctor

However, operator= calling an Init() method will provide only the basic exception guarantee, which is generally not preferred when a better implementation exists that provides a strong guarantee. See http://www.cplusplus.com/forum/articles/18749/ for details on an exception-safe (providing strong guarantee) assignment operator.

[kooth]

Thanks, I'll check it out!