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Re: Is there ToNumber?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg119607] Re: Is there ToNumber?
  • From: ADL <alberto.dilullo at tiscali.it>
  • Date: Sun, 12 Jun 2011 05:07:24 -0400 (EDT)
  • References: <isnllk$n7b$1@smc.vnet.net> <201106090945.FAA06238@smc.vnet.net>

On 11 Giu, 12:52, "Dr. Peter Klamser" <klam... at googlemail.com> wrote:
> ... ToExpression["1+1"]
>
> One Hint: If you know a function in Mathematica like "ToString", you
> mentioned in your email, look in the help system in the section "see
> also", there you find ToExpression["1+1"].
>
> Kind regards
>
> Peter
>
> Am 11.06.2011 09:59, schrieb Ted Sariyski:
>
> > Hi,
> > Is there a built-in function which returns the numeric value of a string
> > (like ToString but inverse).  Currently I use mine function toNumber:
>
> >    ch = StringToStream[timeStr];
> >    timeNum = Read[ch, Number];
> >    Close[ch];
>
> > but I suspect there is easier way.
> > Thanks in advance,
> > --Ted
>
> --
> Mit freundlichen Gr en
>
> Uta&  Peter Klamser

The request is less trivial than ToExpression["1+1"] since, for
example, typical number format cannot be read into Mathematica without
the rather involved trick reported by Ted Sariyski. As an example,

ToExpression["1e3"]
==> e3


ch = StringToStream["1e3"];
timeNum = Read[ch, Number];
Close[ch];
timeNum
==> 1000

I feel this complication as rather unfortunate, unless I am also
missing a simpler way to read in numbers.

ADL


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