variable has numeric value?

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hello,
I want to write a script that can check if a variable's value is numeric or not.
In perlfaq I came across this:

if (/\D/)            { print "has nondigits\n" }
    if (/^\d+$/)         { print "is a whole number\n" }
    if (/^-?\d+$/)       { print "is an integer\n" }
    if (/^[+-]?\d+$/)    { print "is a +/- integer\n" }
    if (/^-?\d+\.?\d*$/) { print "is a real number\n" }
    if (/^-?(?:\d+(?:\.\d*)?|\.\d+)$/) { print "is a decimal number\n"
+ }
    if (/^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?$/)
            { print "a C float\n" }
[download]

Does this cover (i,e. exclude as wrong) examples like -.5 or 16F, etc?

Comment on variable has numeric value? Select or Download Code

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Re: variable has numeric value? by choroba (Cardinal) on Mar 11, 2014 at 14:05 UTC
To test it, just copy and paste the above code to your text editor, and add the following at the beginning: `for ('-.5', '16F') {` [download] and add a closing curly bracket at the end. Then try to run the resulting script and see. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re: variable has numeric value? by toolic (Bishop) on Mar 11, 2014 at 14:22 UTC
See also `looks_like_number` in Scalar::Util	[reply] [d/l]
Re: variable has numeric value? by hazylife (Monk) on Mar 11, 2014 at 14:22 UTC
See `strtod()` in the POSIX package.	[reply] [d/l]
Re: variable has numeric value? by ww (Archbishop) on Mar 11, 2014 at 14:42 UTC
If the "perlfaq" context suggests this was supposedto illusatrate how to determine the characteristics of a possible numeric var, FILE A BUG REPORT! BUT, are you sure that's what intended? Can you provide a link to that section of the faq? *Questions containing the words "doesn't work* (or their moral equivalent) unless accompanied by:** code verbatim error and/or warning messages a coherent explanation of what "doesn't work actually means ... will usually get a downvote from me.	[reply]
Re^2: variable has numeric value? by Anonymous Monk on Mar 11, 2014 at 20:43 UTC
If the "perlfaq" ... FILE A BUG REPORT!... Or update your perlfaq and see what the latest says before deciding to file a report :)	[reply]