dev-cpp-users

Re: [Dev-C++] How to get the number of elements in an array

[Daniel G. <sp...@ho...>]

I tried that but it returns the size of the first element in the array (or 
whatever the pointer is pointing to).
To set Size I called a function and it returns 320 (bytes required). This is 
most troubling as I should know this! lol

Daniel


>From: "Paul Muehlbach" <tr...@gm...>
>To: "Daniel Glenfield" <sp...@ho...>
>Subject: Re: [Dev-C++] How to get the number of elements in an array
>Date: Tue, 20 Jan 2004 14:04:00 +0100 (MET)
>
> > This is an easy Q I know but I can't think how to do it...
> >
> > Size = 9;  // Decided by a function but set to 9 for this example
> >
> > int* Buf = new int[Size];
> >
> > int Tmp = sizeof(Buf);
> >
> > This can't be right. How do I get the size? Len(Buf) and Length(Buf) are
> > not
> > recognised (I thought they were functions but I guess not).
> >
> > Any thoughts?
> >
>
>try
>
>Tmp = sizeof(*Buf);
>
>(sorry,but normally,i use c-array functions ^^°)
>
>traexx
>
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Re: [Dev-C++] How to get the number of elements in an array

[Daniel G. <sp...@ho...>]

And I can't use a for loop and increment the pointer until it reaches the 
end of the array because that is not safe, according to Code Complete. Any 
more ideas? Maybe this isn't so easy after all! lol


>From: Per Westermark <pw...@ia...>
>To: Mohammed Iqbal <mi...@ac...>
>CC: Daniel Glenfield <sp...@ho...>,      
><dev...@li...>
>Subject: Re: [Dev-C++] How to get the number of elements in an array
>Date: Tue, 20 Jan 2004 17:21:41 +0100 (CET)
>
>The idea was good, but it only works for statically allocated arrays.
>When the array is dynamically allocated, it isn't possible to check number
>of entries. Some low-level functions might return size of the memory block
>but that is highly nonportable, and it still doesn't answer number of
>array entries, since the allocated block will almost always be rounded up
>to a larger size.
>
>/Per W
>
>On Tue, 20 Jan 2004, Mohammed Iqbal wrote:
>
> > n_of_elements=sizeof(Buf)/sizeof(Buf[0]);
> >
> > Mohammed
> > ----- Original Message -----
> > From: "Daniel Glenfield" <sp...@ho...>
> > To: <dev...@li...>
> > Sent: Tuesday, January 20, 2004 1:49 PM
> > Subject: [Dev-C++] How to get the number of elements in an array
> >
> >
> > > This is an easy Q I know but I can't think how to do it...
> > >
> > > Size = 9;  // Decided by a function but set to 9 for this example
> > >
> > > int* Buf = new int[Size];
> > >
> > > int Tmp = sizeof(Buf);
> > >
> > > This can't be right. How do I get the size? Len(Buf) and Length(Buf) 
>are
> > not
> > > recognised (I thought they were functions but I guess not).
> > >
> > > Any thoughts?
> > >
> > > _________________________________________________________________
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Re: [Dev-C++] How to get the number of elements in an array

[<or...@vp...>]

Daniel Glenfield wrote:
> And I can't use a for loop and increment the pointer until it reaches 
> the end of the array because that is not safe, according to Code 
> Complete. Any more ideas? Maybe this isn't so easy after all! lol

As Per Westermark noted, correctly, the ONLY one safe method is to store 
the size separately.

Another (not so safe) alternative might be to use a special array 
element, which marks the end of the array. This is something, what 
char[] arrays use: the '\0' character, but you can use whatever you 
want. BUT, this method is not really the best, as getting the size 
requires you to iterate through the array, which can be very inefficient 
at large array sizes.

So, just store the size in a separate counter, that's how most people do 
it, there's no wrong about it, actually, that's the best known method 
nowadays. You can safely use it.

--
Greetings,
   Balázs