• QueenSvetlana (23/23) Aug 19 2018 When using the .length property of a dynamic array why does it
• Chris M. (5/29) Aug 19 2018 auto appendNumber = appender(arrayofNumbers);
• Chris M. (4/10) Aug 19 2018 Whoops
• QueenSvetlana (6/19) Aug 19 2018 New to d programming here :D Bare with me.
• Chris M. (2/25) Aug 19 2018 Yes, the .data field gives the array you're working on.
• Simen =?UTF-8?B?S2rDpnLDpXM=?= (24/47) Aug 19 2018 I suggest reading the D tour's page on arrays:

QueenSvetlana <svetlanalilyrosemond gmail.com> writes:

When using the .length property of a dynamic array why does it 
return the incorrect number of elements after I use the appender?

import std.stdio;
import std.array : appender;

void main()
{
     //declaring a dynamic array
     int [] arrayofNumbers;
     //append an element using the ~= syntax
     arrayofNumbers ~= 1;
     arrayofNumbers ~= 2;
     //print the array
     writeln(arrayofNumbers);

     //Using appender
     auto appendNumber = appender(arrayofNumbers);
     appendNumber.put(10);
     writeln(appendNumber.data);

     writeln(arrayofNumbers.length);

}

Output:

[1, 2]
[1, 2, 10]
2  --- > Should be 3

Chris M. <chrismohrfeld comcast.net> writes:

On Sunday, 19 August 2018 at 15:44:07 UTC, QueenSvetlana wrote:
 When using the .length property of a dynamic array why does it 
 return the incorrect number of elements after I use the 
 appender?

 import std.stdio;
 import std.array : appender;

 void main()
 {
     //declaring a dynamic array
     int [] arrayofNumbers;
     //append an element using the ~= syntax
     arrayofNumbers ~= 1;
     arrayofNumbers ~= 2;
     //print the array
     writeln(arrayofNumbers);

     //Using appender
     auto appendNumber = appender(arrayofNumbers);
     appendNumber.put(10);
     writeln(appendNumber.data);

     writeln(arrayofNumbers.length);

 }

 Output:

 [1, 2]
 [1, 2, 10]
 2  --- > Should be 3

auto appendNumber = appender(arrayofNumbers);

This returns a separate object. You probably meant to put this 
for the last line

writeln(appendNumber.length);

Chris M. <chrismohrfeld comcast.net> writes:

On Sunday, 19 August 2018 at 15:49:18 UTC, Chris M. wrote:
 On Sunday, 19 August 2018 at 15:44:07 UTC, QueenSvetlana wrote:
 [...]

 auto appendNumber = appender(arrayofNumbers);

 This returns a separate object. You probably meant to put this 
 for the last line

 writeln(appendNumber.length);

Whoops

writeln(appendNumber.data.length);

https://run.dlang.io/is/4aNx1l

QueenSvetlana <svetlanalilyrosemond gmail.com> writes:

On Sunday, 19 August 2018 at 15:53:25 UTC, Chris M. wrote:
 On Sunday, 19 August 2018 at 15:49:18 UTC, Chris M. wrote:
 On Sunday, 19 August 2018 at 15:44:07 UTC, QueenSvetlana wrote:
 [...]

 auto appendNumber = appender(arrayofNumbers);

 This returns a separate object. You probably meant to put this 
 for the last line

 writeln(appendNumber.length);

 Whoops

 writeln(appendNumber.data.length);

 https://run.dlang.io/is/4aNx1l

New to d programming here :D Bare with me.

The object that is returned by appendNumber.data is an array 
reflecting the elements I added using appendNumber correct? So I 
would have the call length on appendNumber.data instead of the 
original array?

Chris M. <chrismohrfeld comcast.net> writes:

On Sunday, 19 August 2018 at 16:03:06 UTC, QueenSvetlana wrote:
 On Sunday, 19 August 2018 at 15:53:25 UTC, Chris M. wrote:
 On Sunday, 19 August 2018 at 15:49:18 UTC, Chris M. wrote:
 On Sunday, 19 August 2018 at 15:44:07 UTC, QueenSvetlana 
 wrote:
 [...]

 auto appendNumber = appender(arrayofNumbers);

 This returns a separate object. You probably meant to put 
 this for the last line

 writeln(appendNumber.length);

 Whoops

 writeln(appendNumber.data.length);

 https://run.dlang.io/is/4aNx1l

 New to d programming here :D Bare with me.

 The object that is returned by appendNumber.data is an array 
 reflecting the elements I added using appendNumber correct? So 
 I would have the call length on appendNumber.data instead of 
 the original array?

Yes, the .data field gives the array you're working on.

Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:

On Sunday, 19 August 2018 at 16:03:06 UTC, QueenSvetlana wrote:
 On Sunday, 19 August 2018 at 15:53:25 UTC, Chris M. wrote:
 On Sunday, 19 August 2018 at 15:49:18 UTC, Chris M. wrote:
 On Sunday, 19 August 2018 at 15:44:07 UTC, QueenSvetlana 
 wrote:
 [...]

 auto appendNumber = appender(arrayofNumbers);

 This returns a separate object. You probably meant to put 
 this for the last line

 writeln(appendNumber.length);

 Whoops

 writeln(appendNumber.data.length);

 https://run.dlang.io/is/4aNx1l

 New to d programming here :D Bare with me.

 The object that is returned by appendNumber.data is an array 
 reflecting the elements I added using appendNumber correct? So 
 I would have the call length on appendNumber.data instead of 
 the original array?

I suggest reading the D tour's page on arrays:
https://tour.dlang.org/tour/en/basics/arrays

In short, D arrays (more correctly called slices) are structs 
that look like this:

struct Slice(T) {
     T* ptr;
     size_t length;
}

As the name Slice indicates, it represents a slice of memory, 
with a beginning address and a length. If you have two int[] 
instances (let's call them A and B) that point to the same data, 
they have their own copy of the ptr and length fields, and 
changing the value of a field in A will not change the 
corresponding field in B.

When you append to A, what's happening* is the length is 
increased, and the appended data is written to the end of the 
memory pointed to. B does not see this, since it only looks at 
the first <length> elements of that block.

--
   Simen

* Plus some checking of the length of the block of memory it's 
pointing to, and possible reallocation if the block isn't big 
enough.