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Re: char* to literal return from static in-class method definition - will the pointer always be the same?

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On 01/ 4/12 08:17 AM, avasilev wrote:

Please don't snip attributions.

>> Don't compare pointers.  Compare the string contents.  If you want to
>> ensure that the pointers are always the same, create an object and
>> return its address.  There is no guarantee that two literals have the
>> same address if their contents match.  It's *usually* the case since the
>> linker merges those.  The language doesn't require it, though.
>>
>> Probably better to do
>>
>>      class MyClass
>>      {
>>      public:
>>         static char const* typeName() {
>>            static const char name[] = "myClass"; return name; }
>>      };
>>
>
> Let me clarify a bit more on the use case. I actually have only one
> place in code where the literal is - namely the typeName()method. The
> class can be regarded as a factory, which creates objects, which have
> a char pointer field, which the factory assigns to the return value of
> typeName(). Later, when a function is called, taking such an object as
> argument, it does type checking by calling typeName() of the factory,
> and comparing the returned pointer to the object's field.

That's why Victor suggested a local static object: the address will be 
unique.

-- 
Ian Collins

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char* to literal return from static in-class method definition - will the pointer always be the same? avasilev <alxvasilev@gmail.com> - 2012-01-03 10:00 -0800
  Re: char* to literal return from static in-class method definition - will the pointer always be the same? Victor Bazarov <v.bazarov@comcast.invalid> - 2012-01-03 13:50 -0500
    Re: char* to literal return from static in-class method definition - will the pointer always be the same? avasilev <alxvasilev@gmail.com> - 2012-01-03 11:04 -0800
    Re: char* to literal return from static in-class method definition - will the pointer always be the same? avasilev <alxvasilev@gmail.com> - 2012-01-03 11:17 -0800
      Re: char* to literal return from static in-class method definition -   will the pointer always be the same? Ian Collins <ian-news@hotmail.com> - 2012-01-04 08:37 +1300
    Re: char* to literal return from static in-class method definition - will the pointer always be the same? avasilev <alxvasilev@gmail.com> - 2012-01-03 11:07 -0800
  Re: char* to literal return from static in-class method definition - will the pointer always be the same? Goran <goran.pusic@gmail.com> - 2012-01-03 23:47 -0800
    Re: char* to literal return from static in-class method definition - will the pointer always be the same? avasilev <alxvasilev@gmail.com> - 2012-01-04 04:15 -0800
      Re: char* to literal return from static in-class method definition - will the pointer always be the same? Goran <goran.pusic@gmail.com> - 2012-01-05 00:30 -0800
    Re: char* to literal return from static in-class method definition - will the pointer always be the same? Victor Bazarov <v.bazarov@comcast.invalid> - 2012-01-04 08:43 -0500

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