Digital Mars - c++ - compiler allows assign to const variable

↑ ↓ ← → "Steve Strand" <snstrand comcast.net> writes:

Version 8.40.2 of the compiler does not catch this const violation.


struct test {
    int data[5];
};

void foo(test const& aa)
{
    aa.data[0]= 0;      //compiler allows assign to const variable
}

int main()
{
    test aa;
    foo(aa);
}

Mar 31 2004

↑ ↓ ← → -scooter- <scottm cs.ucla.edu> writes:

Steve Strand wrote:

 Version 8.40.2 of the compiler does not catch this const violation.
 
 
 struct test {
     int data[5];
 };
 
 void foo(test const& aa)



I read that declaration as "a constant reference to test", not "a reference 
to constant test", which would be "const test &".

constant references are redundant, since a reference can't be reseated. 
Thus, it's not a bug, it's really a feature. :-)


-scooter

Apr 01 2004

↑ ↓ ← → Heinz Saathoff <hsaat bre.ipnet.de> writes:

Hello,

-scooter- wrote...
 void foo(test const& aa)


 
 I read that declaration as "a constant reference to test", not "a reference 
 to constant test", which would be "const test &".


No, aa is a reference to a const test. The above declaration is the same 
as
    void foo(const test& aa);

I don't know if const is allowed for references (I assume not because it 
makes no sense as you already stated), but if, than a const ref could be 
declared as
     void foo(test &const a); 

Using a pointer instead of reference such a declaration makes sense:
     void foo(test * const a);  // a is a const pointer to test


- Heinz

Apr 02 2004

↑ ↓ ← → "Matthew" <matthew stlsoft.org> writes:

"-scooter-" <scottm cs.ucla.edu> wrote in message
news:c4ho5t$pnd$1 digitaldaemon.com...
 Steve Strand wrote:

 Version 8.40.2 of the compiler does not catch this const violation.


 struct test {
     int data[5];
 };

 void foo(test const& aa)



 I read that declaration as "a constant reference to test", not "a


 to constant test", which would be "const test &".


Then you read it wrong. It is a reference to const data, whether

    void foo(test const& aa);

or

    void foo(const test& aa);

What you're talking about would be a

    void foo(test& const aa);

which is not allowed because it is superfluous. A reference cannot be
"re-pointed", so there's no need to account for such a qualifier. That's the
whole point of references.

Apr 03 2004

↑ ↓ ← → Scott Michel <scottm cs.ucla.edu> writes:

Matthew wrote:

 Version 8.40.2 of the compiler does not catch this const violation.


 struct test {
     int data[5];
 };

 void foo(test const& aa)



 I read that declaration as "a constant reference to test", not "a


 to constant test", which would be "const test &".


 Then you read it wrong. It is a reference to const data, whether
 
     void foo(test const& aa);
 
 or
 
     void foo(const test& aa);


I sit corrected. After looking at Dan Saks' writing on the subject (his wife
teaches CS at my undergrad institution): While legit, I don't agree with
the notation as it leads to incorrect interpretation, like mine. Of course,
I've disagreed with Dan before.

Apr 06 2004