Why does std.file.readText() append a Line Feed char onto the end of the string?

I have a file with the following contents in it:
Name   =               Int
Other=Float
One More = String(Random;)

I then have the code:

void main(string[] args){
    const text = "Name   =               Int
Other=Float
One More = String(Random;)";

    string input = readText(args[1]);

    writefln("Raw data");
    writefln("D)    %s", cast(ubyte[])text[$-5..$]);
    writefln("File) %s", cast(ubyte[])input[$-5..$]);

}

This produces:
Raw data
D)    [100, 111, 109, 59, 41]
File) [111, 109, 59, 41, 10]

Any Idea why the reading from the File adds on that extra '10' character?

I don't think it's my editor adding chars to the end of the file, as I'm using vi.

On Thu, 18 Dec 2014 09:18:35 +0000
Colin via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:

> Why does std.file.readText() append a Line Feed char onto the end of the string?
> 
> I have a file with the following contents in it:
> Name   =               Int
> Other=Float
> One More = String(Random;)
> 
> I then have the code:
> 
> void main(string[] args){
>      const text = "Name   =               Int
> Other=Float
> One More = String(Random;)";
> 
>      string input = readText(args[1]);
> 
>      writefln("Raw data");
>      writefln("D)    %s", cast(ubyte[])text[$-5..$]);
>      writefln("File) %s", cast(ubyte[])input[$-5..$]);
> 
> }
> 
> This produces:
> Raw data
> D)    [100, 111, 109, 59, 41]
> File) [111, 109, 59, 41, 10]
> 
> Any Idea why the reading from the File adds on that extra '10' character?
> 
> I don't think it's my editor adding chars to the end of the file, as I'm using vi.

you *definetely* has the last line ended with '\n'.

On Thursday, 18 December 2014 at 09:25:47 UTC, ketmar via Digitalmars-d-learn wrote:
> On Thu, 18 Dec 2014 09:18:35 +0000
> Colin via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:
>
>> Why does std.file.readText() append a Line Feed char onto the end of the string?
>> 
>> I have a file with the following contents in it:
>> Name   =               Int
>> Other=Float
>> One More = String(Random;)
>> 
>> I then have the code:
>> 
>> void main(string[] args){
>>      const text = "Name   =               Int
>> Other=Float
>> One More = String(Random;)";
>> 
>>      string input = readText(args[1]);
>> 
>>      writefln("Raw data");
>>      writefln("D)    %s", cast(ubyte[])text[$-5..$]);
>>      writefln("File) %s", cast(ubyte[])input[$-5..$]);
>> 
>> }
>> 
>> This produces:
>> Raw data
>> D)    [100, 111, 109, 59, 41]
>> File) [111, 109, 59, 41, 10]
>> 
>> Any Idea why the reading from the File adds on that extra '10' character?
>> 
>> I don't think it's my editor adding chars to the end of the file, as I'm using vi.
>
> you *definetely* has the last line ended with '\n'.

I dont see how, I copy and pasted from the string definition in D, directly after the first " and directly before the last ".

If I look at the file in vim with line numbers turned on, the file is like this. So I really dont think I have a new line in the file...

  1 Name   =               Int
  2 Other=Float
  3 One More = String(Random;)

On Thursday, 18 December 2014 at 10:16:38 UTC, Colin wrote:
> On Thursday, 18 December 2014 at 09:25:47 UTC, ketmar via Digitalmars-d-learn wrote:
>> On Thu, 18 Dec 2014 09:18:35 +0000
>> Colin via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:
>>
>>> Why does std.file.readText() append a Line Feed char onto the end of the string?
>>> 
>>> I have a file with the following contents in it:
>>> Name   =               Int
>>> Other=Float
>>> One More = String(Random;)
>>> 
>>> I then have the code:
>>> 
>>> void main(string[] args){
>>>     const text = "Name   =               Int
>>> Other=Float
>>> One More = String(Random;)";
>>> 
>>>     string input = readText(args[1]);
>>> 
>>>     writefln("Raw data");
>>>     writefln("D)    %s", cast(ubyte[])text[$-5..$]);
>>>     writefln("File) %s", cast(ubyte[])input[$-5..$]);
>>> 
>>> }
>>> 
>>> This produces:
>>> Raw data
>>> D)    [100, 111, 109, 59, 41]
>>> File) [111, 109, 59, 41, 10]
>>> 
>>> Any Idea why the reading from the File adds on that extra '10' character?
>>> 
>>> I don't think it's my editor adding chars to the end of the file, as I'm using vi.
>>
>> you *definetely* has the last line ended with '\n'.
>
> I dont see how, I copy and pasted from the string definition in D, directly after the first " and directly before the last ".
>
> If I look at the file in vim with line numbers turned on, the file is like this. So I really dont think I have a new line in the file...
>
>   1 Name   =               Int
>   2 Other=Float
>   3 One More = String(Random;)

You can make sure using `hexdump -C file`. I tested locally creating a file using vi, and it does indeed have a '\n' at the end of file.

On Thursday, 18 December 2014 at 10:43:32 UTC, yazd wrote:
> On Thursday, 18 December 2014 at 10:16:38 UTC, Colin wrote:
>> On Thursday, 18 December 2014 at 09:25:47 UTC, ketmar via Digitalmars-d-learn wrote:
>>> On Thu, 18 Dec 2014 09:18:35 +0000
>>> Colin via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:
>>>
>>>> Why does std.file.readText() append a Line Feed char onto the end of the string?
>>>> 
>>>> I have a file with the following contents in it:
>>>> Name   =               Int
>>>> Other=Float
>>>> One More = String(Random;)
>>>> 
>>>> I then have the code:
>>>> 
>>>> void main(string[] args){
>>>>    const text = "Name   =               Int
>>>> Other=Float
>>>> One More = String(Random;)";
>>>> 
>>>>    string input = readText(args[1]);
>>>> 
>>>>    writefln("Raw data");
>>>>    writefln("D)    %s", cast(ubyte[])text[$-5..$]);
>>>>    writefln("File) %s", cast(ubyte[])input[$-5..$]);
>>>> 
>>>> }
>>>> 
>>>> This produces:
>>>> Raw data
>>>> D)    [100, 111, 109, 59, 41]
>>>> File) [111, 109, 59, 41, 10]
>>>> 
>>>> Any Idea why the reading from the File adds on that extra '10' character?
>>>> 
>>>> I don't think it's my editor adding chars to the end of the file, as I'm using vi.
>>>
>>> you *definetely* has the last line ended with '\n'.
>>
>> I dont see how, I copy and pasted from the string definition in D, directly after the first " and directly before the last ".
>>
>> If I look at the file in vim with line numbers turned on, the file is like this. So I really dont think I have a new line in the file...
>>
>>  1 Name   =               Int
>>  2 Other=Float
>>  3 One More = String(Random;)
>
> You can make sure using `hexdump -C file`. I tested locally creating a file using vi, and it does indeed have a '\n' at the end of file.

Ah, I see. That's a little annoying.
Thanks folks!

On Thursday, 18 December 2014 at 09:18:36 UTC, Colin wrote:
> I don't think it's my editor adding chars to the end of the file, as I'm using vi.

:-) vim actually does it by default. Check out ":help eol" from inside it.

I think other vi clones do it too but I'm not sure, but I know vim has it as documented behavior.

There's apparently a few reasons for it:
http://stackoverflow.com/questions/729692/why-should-files-end-with-a-newline

On 12/18/2014 02:51 AM, Colin wrote:

> > vi, and it does indeed have a '\n' at the end of file.
>
> Ah, I see. That's a little annoying.

It looks like there are ways of dealing with it:


http://stackoverflow.com/questions/1050640/vim-disable-automatic-newline-at-end-of-file

Ali
"happy with Emacs :p"

On Thursday, 18 December 2014 at 22:29:30 UTC, Ali Çehreli wrote:
> On 12/18/2014 02:51 AM, Colin wrote:
>
> > > vi, and it does indeed have a '\n' at the end of file.
> >
> > Ah, I see. That's a little annoying.
>
> It looks like there are ways of dealing with it:
>
>
> http://stackoverflow.com/questions/1050640/vim-disable-automatic-newline-at-end-of-file
>
> Ali
> "happy with Emacs :p"

Does emacs do this aswell? :)

Anyway, I'm making a tool which will be in use by a range of
people, so making the tool accept inputs with \n or not would be
the better choice than getting everyone to ensure they dont have
\n at the end of every file.

On Fri, 19 Dec 2014 10:22:01 +0000
Colin via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:

> On Thursday, 18 December 2014 at 22:29:30 UTC, Ali Çehreli wrote:
> > On 12/18/2014 02:51 AM, Colin wrote:
> >
> > > > vi, and it does indeed have a '\n' at the end of file.
> > >
> > > Ah, I see. That's a little annoying.
> >
> > It looks like there are ways of dealing with it:
> >
> >
> > http://stackoverflow.com/questions/1050640/vim-disable-automatic-newline-at-end-of-file
> >
> > Ali
> > "happy with Emacs :p"
> 
> Does emacs do this aswell? :)
> 
> Anyway, I'm making a tool which will be in use by a range of people, so making the tool accept inputs with \n or not would be the better choice than getting everyone to ensure they dont have \n at the end of every file.
`.strip` the read string. or just `.stripRight`. this will remove all
unnecessary whitespace noise at both sides of string (`.strip`) or only
at the end of the string (`.stripRight`).

On Fri, 19 Dec 2014 10:22:01 +0000
Colin via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:

> On Thursday, 18 December 2014 at 22:29:30 UTC, Ali Çehreli wrote:
> > On 12/18/2014 02:51 AM, Colin wrote:
> >
> > > > vi, and it does indeed have a '\n' at the end of file.
> > >
> > > Ah, I see. That's a little annoying.
> >
> > It looks like there are ways of dealing with it:
> >
> >
> > http://stackoverflow.com/questions/1050640/vim-disable-automatic-newline-at-end-of-file
> >
> > Ali
> > "happy with Emacs :p"
> 
> Does emacs do this aswell? :)
> 
> Anyway, I'm making a tool which will be in use by a range of people, so making the tool accept inputs with \n or not would be the better choice than getting everyone to ensure they dont have \n at the end of every file.

p.s. in D string slicing cost almost nothing and it doesn't need to scan the whole string to find it's length, so stripping is very cheap.