Re: What's the cause of extra new line with Text_IO when program exit

[Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>]

On 08/15/2013 06:02 PM, Zhu, Qun-Ying wrote:
>
> When executing, they have different behavior.
>
> For hello, you have:
> # ./hello
> Hello World!
> #
>
> While for hello_stream, you got:
> # ./hello_stream
> Hello World!#
>
> If change the last Put to Put_Line for hello, you got the same result.
> I would like to know why it is like that.

Ada.Text_IO writes to a text file of type Ada.Text_IO.File_Type; Hello writes to 
the file Standard_Output. Text files consist of lines of text; lines are 
conceptually terminated by a line terminator. For a version of Unix such as you 
seem to be using, the conceptual terminator is an actual LF character.

While it is not defined by the language what happens to a File_Type when the 
program ends [ARM A.7(6)], it does require that File_Type have finalization [ARM 
A.10.1(86)]. A logical thing for this finalization to do is to make sure that 
the last line is terminated, and it appears that your implementation does this.

A stream is a different creature than a text file, and doesn't know about lines 
or terminators, so it should not be surprising that it adds no terminator.

-- 
Jeff Carter
"It is the German who is so uncourteous to his verbs."
A Scandal in Bohemia
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