Re: variable lenght strings

[Martin Krischik <krischik@users.sourceforge.net>]

Pascal Obry wrote:

> 
> Martin Krischik <krischik@users.sourceforge.net> writes:
> 
>> functionￜGet_Lineￜ(
>> Fileￜ:ￜinￜIO.File_Type)
>> return
>> String
>> is
>> Bufferￜ:ￜStringￜ(1ￜ..ￜBufferSize);
>> Lastￜￜￜ:ￜNatural;
>> begin
>> IO.Get_Lineￜ(
>> Fileￜ=>ￜFile,
>> Itemￜ=>ￜBuffer,
>> Lastￜ=>ￜLast);
>> 
>> ifￜLastￜ<ￜBuffer'Lastￜthen
>> returnￜBufferￜ(1ￜ..ￜLast);
>> elsifￜIO.End_Of_Fileￜ(File)ￜthen
>> returnï¿œBuffer;
>> else
>> returnￜBufferￜ&ￜGet_Lineￜ(File);
>            ^^^^^^^^^^^^^^^^^^^^^^^^^^
>          
> This kind of recursivity is very dangerous and could cause a stack
> overflow. It is better to use a non recursive version and to store the
> result into an Unbounded_String for example.

In fact I have got an non recursive version returning an Unbounded_String 
as well:

ￜￜￜfunctionￜGet_Lineￜ(
ￜￜￜￜￜￜFileￜ:ￜinￜIO.File_Type)
ￜￜￜreturn
ￜￜￜￜￜￜS_U.Unbounded_String
ￜￜￜis

ￜￜￜￜￜￜRetvalￜ:ￜS_U.Unbounded_Stringￜ:=ￜS_U.Null_Unbounded_String;
ￜￜￜￜￜￜItemￜￜￜ:ￜStringￜ(1ￜ..ￜBufferSize);
ￜￜￜￜￜￜLastￜￜￜ:ￜNatural;
ￜￜￜbegin
ￜￜￜￜￜￜGetWholeLineￜ:
ￜￜￜￜￜￜloop
ￜￜￜￜￜￜￜￜￜIO.Get_Lineￜ(
ￜￜￜￜￜￜￜￜￜￜￜￜFileￜ=>ￜFile,
ￜￜￜￜￜￜￜￜￜￜￜￜItemￜ=>ￜItem,
ￜￜￜￜￜￜￜￜￜￜￜￜLastￜ=>ￜLast);

ￜￜￜￜￜￜￜￜￜS_U.Appendￜ(
ￜￜￜￜￜￜￜￜￜￜￜￜSourceￜￜￜ=>ￜRetval,
ￜￜￜￜￜￜￜￜￜￜￜￜNew_Itemￜ=>ￜItemￜ(1ￜ..ￜLast));

ￜￜￜￜￜￜￜￜￜexitￜGetWholeLineￜwhenￜLastￜ<ￜItem'Last
ￜￜￜￜￜￜￜￜￜￜￜￜￜￜￜￜￜￜￜￜￜￜorￜￜￜIO.End_Of_Fileￜ(File);

ￜￜￜￜￜￜendￜloopￜGetWholeLine;

ￜￜￜￜￜￜreturnￜRetval;
ￜￜￜendￜGet_Line;

With Regards

Martin

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