Solved

MyMethod()const ..question

Posted on 1998-11-27
2
194 Views
Last Modified: 2010-04-01
suppose I have two classes with a const method in the
derived class:
class A
{
 int m_nX;
};
class B : public A
{
 int m_nY;
 int GetValue() const
 { return m_nY; }
};
in this case everthing is allright.
the question: is it legal/proper to do something like
class B : public A
{
 int m_nY;
 int GetValue() const
 {
  m_nX = 4;
  return m_nY;
 }
};
concerning the const method "GetValue()" ???
0
Comment
Question by:nil_dib
2 Comments
 
LVL 86

Accepted Solution

by:
jkr earned 80 total points
ID: 1178746
Assuming that m_nX is a mebmer of 'B', this statement is not legal, as functions that are declared 'const' may not alter _any_ member variable (the compiler will also complain ;-).
0
 
LVL 22

Expert Comment

by:nietod
ID: 1178747
Note that on compilers that support it, the m_nX member could be declared mutable.  mutable members may be changed from const functions.  However, indiscriminate use of "mutable" discouraged

Note also that m_nX is a private member of the base class.  Thus the error you will get is that m_nX is undefined, not that it is constant.  If it were made public or protected, then you would get the error that it is constant.
0

Featured Post

ScreenConnect 6.0 Free Trial

Want empowering updates? You're in the right place! Discover new features in ScreenConnect 6.0, based on partner feedback, to keep you business operating smoothly and optimally (the way it should be). Explore all of the extras and enhancements for yourself!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Go is an acronym of golang, is a programming language developed Google in 2007. Go is a new language that is mostly in the C family, with significant input from Pascal/Modula/Oberon family. Hence Go arisen as low-level language with fast compilation…
Container Orchestration platforms empower organizations to scale their apps at an exceptional rate. This is the reason numerous innovation-driven companies are moving apps to an appropriated datacenter wide platform that empowers them to scale at a …
The goal of the video will be to teach the user the difference and consequence of passing data by value vs passing data by reference in C++. An example of passing data by value as well as an example of passing data by reference will be be given. Bot…
The viewer will learn how to clear a vector as well as how to detect empty vectors in C++.

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question