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MathGroup Archive 2004

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Re: If and openwrite and openappend

  • To: mathgroup at smc.vnet.net
  • Subject: [mg49193] Re: If and openwrite and openappend
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Wed, 7 Jul 2004 01:42:26 -0400 (EDT)
  • Organization: Universitaet Leipzig
  • References: <ccdm2a$sf6$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,


nix[x_String, y_String] := Module[{t},
    t = {x, y};
If[FileType["dBaspap"] === None, 
   stmp = OpenWrite["dBaspap"], 
   stmp = OpenAppend["dBaspap"]];
   Write[stmp, t];
   Close[stmp]
    ]

For two symbols without a value
a==b is left unevaluated and gives not True or False,
you need SameQ[]

Regards
  Jens

"camartin at snet.net" wrote:
> 
> MathGroup,
> 
> Obviously I don't understand something about using If, etc.
> 
> I'm trying to write a piece of code to store strings in a file.  A very
> simplified example follows:
> 
> Clear[t]
> Clear[nix]
> nix[x_String, y_String] :=
>   t = {x, y}
> If[FileType["c:\\Mathematica\\dBaspap"] == None,
>     stmp = OpenWrite["c:\\Mathematica\\dBaspap"],
>   stmp = OpenAppend["c:\\Mathematica\\dBaspap"]]
> Write[stmp, t]
> Close[stmp]
> 
> The function seems to work as I want if the file doesn't exist.  If it
> exists the code doesn't work.
> 
> If I  the OpenAppend from the If statement things work fine.  But a
> subsequent use of nix fails because it refuses to open a stream.
> 
> I've read Wolfram fairly carefully I thought but I'm missing something
> obvious.
> Thanks for any help.
> 
> Cliff Martin


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