Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

const volatile variable

Posted on 1998-09-16
2
Medium Priority
?
835 Views
Last Modified: 2008-02-01
Hi friends,
        can anyone please say me where a constant volatile variable will be used?.
Thanks.
0
Comment
Question by:66
2 Comments
 
LVL 5

Expert Comment

by:ecw
ID: 1172859
maybe a read only device register!
0
 

Accepted Solution

by:
euclid091498 earned 0 total points
ID: 1172860
A variable modified with both const and volatile will be affected by both:

- Because it is const, the compiler will not allow it to be modified BY THE CODE after it is initialized.
- Because it is volatile, the compiler will not attempt agressive optimizations that might depend on the content not being modified EXTERNALLY.

There is an example given in 'The C++ Programming Language" (p 808, 3rd edition):

extern const volatile clock;

"Two successive reads of clock might give different results."
So it is declared volatile.
It is also declared const so that it will not be possible to modify it IN THE CODE.

0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

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

C++ Properties One feature missing from standard C++ that you will find in many other Object Oriented Programming languages is something called a Property (http://www.experts-exchange.com/Programming/Languages/CPP/A_3912-Object-Properties-in-C.ht…
Article by: evilrix
Looking for a way to avoid searching through large data sets for data that doesn't exist? A Bloom Filter might be what you need. This data structure is a probabilistic filter that allows you to avoid unnecessary searches when you know the data defin…
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
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…
Suggested Courses

782 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