what is advantage pointer-to-member and pointer-to-function

Question

1.00/5 (2 votes)

See more:

Hi everyone,

Last interview, i got a question what is the advantage pointer to data member over the pointer member, normal member function and pointer to function.

Posted 14-Jul-15 18:51pm

Member 11417637

Add a Solution

Comments

Stefan_Lang 15-Jul-15 2:36am

Makes no sense without context: it all depends on the intended use.

Or more to the point, who would be using the pointer to data member and pointer to function? If it's someone outside the class, that would break encapsulation and is generally a bad idea without good reason. If used inside the class, what is the point of using a pointer?

P.S.: is this really, exactly, what you were asked? I have my doubts you've reproduced the question correctly

Richard MacCutchan 15-Jul-15 3:53am

There is no advantage, they are just used in different circumstances.

Member 11417637 15-Jul-15 5:36am

ok richard,
pls explain any one situation

Richard MacCutchan 15-Jul-15 7:47am

You would only need a function pointer when you do not know the function name at compile time, for example:
1. The funtion to call will depend on some inputs in the program.
2. You are calling the function from a DLL that you load at run time.

Member 11417637 15-Jul-15 8:29am

Thanks Richard MacCutchan

Member 11417637 15-Jul-15 8:35am

Mr Richard MacCuthan
could you have help to me on mfc. i have some doubts on mfc

KarstenK 15-Jul-15 7:30am

Sometimes are stupid questions used to make somebody unsure, or the questioner dont know what he is talking. Strange things are happening.

Stefan_Lang 16-Jul-15 2:12am

For the former, the interviewer would have to be rather clever, and in my experience that is much more rare than the interviewer just being dumb. ;-p

P.S.: ok, that formulation is rather unfair - in fact I never met an interviewer playing the kind of psychological games you implied, and that may or may not be related to them being clever. And while I met one interviewer with a pretty decent score on the WTF!-scale, that doesn't necessarily mean he was just being dumb. ;-)

2 solutions

Solution 2

They are different beasts and serve different purposes. So I don't see any 'advantage' in using one or the other.
Are you sure you reported the interview question exactly?

Posted 15-Jul-15 20:58pm

CPallini

v2

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Stefan_Lang · Accepted Answer · 2015-07-15T20:45:00

A general note: in C++ you should avoid using raw pointers (of any kind) as a matter of principle, except for the purpose of writing frameworks specifically designed to help other parts of the system avoiding pointers. What you should use are smart pointers.

Given that, I assume the question is intended as a low level evaluation of your understanding, and thus, the explanations would be as follows:

Pointer to data member:
This breaks encapsulation and should never be used. However, you can use a pointer to const data member as a means to pass a data reference to another function in an efficient way.

Data member pointer:
You can use a pointer as a data member rather than the data itself for similar reasons as you would in a local function, e. g.:
- If you need to pass the data to other functions occasionally, and the data type is expensive to copy, using a pointer is preferable
- If the data could have a NULL value, but the data type doesn't define one, using nullptr as NULL value is an option
- if the class that owns the data can (and is expected to) be copied (a lot), but the data element is not usually modified, it may be more sensible for the instances of the class to share the data element by using a pointer (however, it would be even better to use a smart pointer!)

Member function pointer:
Just forget about that unless you are a highly advanced system/framework programmer. Classes and (virtual) member functions make function pointers of any kind pretty much obsolete, except in compiler programming (in which case you would be the one responsible for making the use of function pointers obsolete)