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C++Talk.NET
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Robert Swan
Guest
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 Posted: Wed Dec 29, 2004 8:46 pm Post subject: Re: post increment not post |
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Ron Natalie wrote:
| Quote: |
The following use of class a is convenient:
a a_inst;
int& b = a;
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Yes, I made an error, should be int& b = a_inst;
| Quote: |
But may do the wrong thing, I assume you meant:
int &b = a_inst;
a_inst ++;
a_inst ++;
What does b evaluate to?
or did you really want to let people change the private
member of a_inst by doing:
b = 5;
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When I reduced my code to create a suitable newsgroup posting I changed
the meaning. The data refered to was not supposed to be private. So if
the only risk is the access to private data then I'm fine. I just wanted
to use the same syntax to initialize a reference from both an int and
another class.
Thanks for your help.
Robert
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Howard
Guest
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| Posted: Mon Jan 03, 2005 5:30 pm Post subject: Re: post increment not post |
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"Ron Natalie" <ron (AT) sensor (DOT) com> wrote
| Quote: | Robert Swan wrote:
I'd like to know why the following program outputs 1, and not 0.
#include
class a {
int v;
public:
a():v(0){}
a& operator++(int) {
v++;
You're missing a return here.
If you return
*this
then, the program should behave like you observed.
The v member is incremented and the side effect applied
before the operator++ returns.
If you want it to behave like a real postincrement, you
need to return a copy of the old object.
a operator++(int) {
a temp(*this);
v++;
return a;
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I take it you meant:
return temp;
?
-Howard
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