RE: [MacPerl] macPerl: first steps!

[RD Francis <rdf@hyperactiveinc.com>]

> From: Marek Stepanek [mailto:mstep@podiuminternational.org]

I see two problems:

> #!perl -w
> print "Enter a temperature in Celsius (i.e. 32 F, 100F):\n";
> $celsius = <STDIN>;

First, you store the user's input in $celsius

> chop ($celsius);
> if ($input =~ m/^([-+]?[0-9]+(\.[0-9]*)?)\s*([CF]?)$/i)

Then, you search the value in $input to see what's in it.  You probably want
to store the initial value in $input, not $celsius.

Second, when I look at your data:
> Enter a temperature in Celsius (i.e. 32 F, 100F):
> + 34 C

I suspect you will run into a second problem.  The regular expression
expects to see
a string that starts with:  ^
(and is to be remembered as $1):  (
 (optionally) a sign:   [-+]?
followed by one or more digits:   [0-9]+
optionally followed by a decimal point, and zero or more
digits (which will be remembered as $2):  (\.[0-9]*)?
followed by zero or more spaces:  \s*
optionally followed by a 'C' or and 'F' (which will be remembered
as  $3):  ([CF]?)
followed by nothing (end of string):  $

The i means that this is case insensitive, so the 'C' could be 'c' and the
'F' could be 'f'

This does not allow for a space between the optional sign and the first
digit.  To accommodate that, use this instead:

if ($input =~ m/^([-+]?\s*[0-9]+(\.[0-9]*)?)\s*([CF]?)$/i)

Hope this helps.  Heck, since I ran this all through my mental parser, not
through Perl itself, hope it's right!

R David Francis
rdf@hyperactiveinc.com
http://www.hyperactiveinc.com 

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