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From: S-Y. Chen on 10 Mar 2010 13:20
Dear All,

I am having a headache about checking if a variable is a number
(floating, double, and integer. Anything that is a numerical value).

If I use

if { [string is alnum "$_var1"] != 1}

The strings like " " or " " (all blanks) will pass the
test, giving

So, is there a simple command to check if a variable is a numerical
number ?

And, is there also a simple command to check of a string is empty, or
just full of blanks ?

Thanks for the help in advance.

regards
S-Y. Chen
From: Don Porter on 10 Mar 2010 13:26
S-Y. Chen wrote:
> So, is there a simple command to check if a variable is a numerical
> number ?

[string is double -strict $var]

--
| Don Porter Mathematical and Computational Sciences Division |
| donald.porter(a)nist.gov Information Technology Laboratory |
| http://math.nist.gov/~DPorter/ NIST |
|______________________________________________________________________|
From: Prof Craver on 10 Mar 2010 13:33
On Mar 10, 1:20 pm, "S-Y. Chen" <shenyeh_c...(a)hotmail.com> wrote:
> Dear All,
>
> I am having a headache about checking if a variable is a number
> (floating, double, and integer. Anything that is a numerical value).

Hi,

You can try something like if {[scan $myinput "%f%c" number
stopper]==1} {bleh}

If $myinput is a number, scan should output 1; if it is whitespace it
should output -1; if it is nonnumerical garbage it should output 0;
and if it is garbage that begins with numerical characters, e.g.
-123abc, it should output 2.

--X
 | 
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