Instead of trying to trap the warning, it's better to use looks_like_number from Scalar::Util, as this gives you the exact internal function that Perl uses to check strings and generate that warning in the first place

Seems that perl doesn't always issue a warning when a variable that doesn't look like a number is used in numeric context: 
C:\>perl -MScalar::Util="looks_like_number" -wle "$r = ''; $x = \$r; p
+rint 'lln' if looks_like_number($x); $x += 1"

C:\>perl -MScalar::Util="looks_like_number" -wle "$x = 'hello'; print 
+'lln' if looks_like_number($x); $x += 1"
Argument "hello" isn't numeric in addition (+) at -e line 1.

C:\>

[download]
For both of those one liners, Scalar::Util::looks_like_number($x) returns a false value, but it's only the second one liner that warns when $x is used in numeric context.

Cheers,
Rob

In reply to Re^2: Converting to number doesn't always work... (updated) by syphilis
in thread Converting to number doesn't always work... by harangzsolt33

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