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Re: writing a function that would print the name of a

• To: mathgroup at smc.vnet.net
• Subject: [mg97673] Re: [mg97609] writing a function that would print the name of a
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Wed, 18 Mar 2009 04:55:47 -0500 (EST)
• Reply-to: hanlonr at cox.net

f1[x_String] :=
  "The variable " <> x <> " contains the value " <>
   ToString[ToExpression[x]]

x = 10

10

f1["x"]

The variable x contains the value 10

SetAttributes[f2, HoldFirst]

f2[x_Symbol] :=
  "The variable " <> ToString[HoldForm[x]] <> " contains the value " <>
   ToString[x]

f2[x]

The variable x contains the value 10



Bob Hanlon


On Tue, Mar 17, 2009 at 8:49 AM , johnclin at hss.caltech.edu wrote:

> I have a question that seems simple but I just could not figure out
> how to do it.
>
> I am trying to write a mathematica function that will print the *name*
> of the variable that I pass to the function as well as the value
> itself.
>
> For example, let's say that I define a variable x = 10.
>
> Now, I want to write a function that will print:
> "The variable x contains the value 10".
>
> I tried something like:
> displayOutput [varToPrint_] := (
> Print["The variable "];
> Print[ToString[varToPrint]]; (* <-- this is the problematic line*)
> Print["contains the value "];
> Print[x];
> )
>
> BTW, I do realize that the following works:
> x = 10;
> Print["The symbol ", HoldForm[x], " has a value of ", x];
>
> So there is something about how Mathematica evaluates expression
> inside a function that I am not understanding. Any suggestions?