Re: [Dev-C++] Crash with macro to template conversion

Sorry about that the correct definition is:
template<class T>
void create(T * ptr, int number, char * f_name = __FILE__, int l_num
=
__LINE__)
{
  ptr = new T[number];
  if ( !ptr )
 {
    perror("malloc failure");
    fprintf( stderr, "Malloc failure @ %s:%d\n", f_name, l_num );
    abort();
  }
}

All the exception stuff was just trying to figure out if an error is
even
occuring.

I am trying to keep to convention. The macro is not my code but code
I am
trying to replace. I am very tempted to change it but I also have
RECREATE
(wraps realloc()) and DESTROY (wraps free() ) which also need to be
replaced. I could use macros to alter the function call but I am
trying to
remove all the macros I can (got some linked list macros to replace
as well)

So...How does one create a refrence to a pointer?

----- Original Message ----- 
From: "Per Westermark" <pw...@ia...>
To: "David McKen" <ci...@ya...>
Cc: "Mailing List, Dev-Cpp" <dev...@li...>
Sent: Friday, February 27, 2004 7:08 AM
Subject: Re: [Dev-C++] Crash with macro to template conversion


> First of all - your create template function is declared to return
void,
> so why do you end it with return ptr?
>
> Second, you send in a T* ptr parameter. Note that since C++ uses
> call-by-value, this will behave like a lokal variable, i.e any
assign to
> ptr will not reflect back to the caller. You should change the
first
> parameter of create to be a reference to a pointer. That way, the
assign
> to ptr will reflect back to the variable obj of the caller.
>
> /Per W
>
> On Fri, 27 Feb 2004, David McKen wrote:
>
> > Ok here is my problem.
> >
> > I want to replace:
> > #define CREATE(result, type, number)                \
> > do                              \
> > {                               \
> >     if (!((result) = (type *) calloc ((number), sizeof(type)))) \
> >     {                               \
> >     perror("malloc failure");               \
> >     fprintf(stderr, "Malloc failure @ %s:%d\n", __FILE__,
__LINE__ );
> > \
> >     abort();                        \
> >     }                               \
> > } while(0)
> >
> > With it's C++ equivalent.
> >
> > So far I have:
> > #define CREATE(result, type, num)    create<type>((result),(num))
> > template<class T>
> > void create(T * ptr, int number, char * f_name = __FILE__, int
l_num
> > =
> > __LINE__)
> > {
> >   try {
> >     ptr = new T[number];
> >   }
> >   catch(bad_alloc& b)
> >   {
> >     perror("malloc failure");
> >     fprintf( stderr, "Malloc failure @ %s:%d\n", f_name, l_num );
> >     abort();
> >   }
> >   if ( !ptr )
> >   {
> >     perror("malloc failure");
> >     fprintf( stderr, "Malloc failure @ %s:%d\n", f_name, l_num );
> >     abort();
> >   }
> >   return ptr;
> > }
> >
> > But the program crashes after the function call when any attempt
to
> > acces
> > the data occours:
> > e.g.
> > OBJ_DATA * obj;
> > CREATE( obj , OBJ_DATA, 1 );
> >
> > obj->some_field = 5; //Crashes here and obj = 0x0 from gdb.
> >
> > Thanks in Advance
> > David McKen
> >
> >
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