Re: question about private member

Alan Johnson <>
Fri, 28 Nov 2008 23:18:05 -0800
<ggqqbe$2lr$> wrote:

On Nov 29, 12:26 pm, red floyd <> wrote: wrote:

I'm assuming you're doing this as a learning exercise, otherwise you
should be using std:;string.> class String

   String & operate=(const String *other)

This is incorrect.
      String& operator=(const String& other)> {

    delete m_data;

Undefined behavior.

  m_data=new char[strlen(other.m_data)+1];

This is bad with regard to exception safety.
       char *tmp = new [strlen(other.m_data) + 1];
       strcpy(tmp, other.m_data);
       delete[] m_data; // note delete[], not delete
       m_data = tmp;

   char *m_data;
in the above calss, why memeber function can access the object other's
private m_data?
according to Principle of Encapsulation ,a boject can not access other
object's private memeber.

Because privacy is at the *CLASS* level, not the object level.
Think about it. How would you write a copy constructor or assignment
operator if you couldn't access the private parts of the "other" object?

maybe you are right.thank you.
i want to say,how difficult c++ is.

While I don't necessarily disagree, this is a strange choice of language
features to use to claim C++ is difficult. That is how private class
members work in pretty much every language I've encountered that
supports the concept.

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