>> Pretty much everything else in Perl is happy to treat undef as 0, why not sort?
> I think you're confused
[...]

Whatcha talkin bout Willis?

D:\>perl -we"print for sort { warn qq,($a)($b),; $a <=> $b } 2, 1, 4 ,
+ undef, undef, 3, 'nan','nan','inf','inf'"
(2)(1) at -e line 1.
Use of uninitialized value in concatenation (.) or string at -e line 1
+.
(4)() at -e line 1.
Use of uninitialized value in numeric comparison (<=>) at -e line 1.
Use of uninitialized value $a in concatenation (.) or string at -e lin
+e 1.
()(3) at -e line 1.
Use of uninitialized value in numeric comparison (<=>) at -e line 1.
(nan)(nan) at -e line 1.
(inf)(inf) at -e line 1.
Use of uninitialized value in concatenation (.) or string at -e line 1
+.
(1)() at -e line 1.
Use of uninitialized value in numeric comparison (<=>) at -e line 1.
(1)(4) at -e line 1.
(2)(4) at -e line 1.
Use of uninitialized value $a in concatenation (.) or string at -e lin
+e 1.
Use of uninitialized value in concatenation (.) or string at -e line 1
+.
()() at -e line 1.
Use of uninitialized value in numeric comparison (<=>) at -e line 1.
Use of uninitialized value in numeric comparison (<=>) at -e line 1.
Use of uninitialized value $a in concatenation (.) or string at -e lin
+e 1.
()(1) at -e line 1.
Use of uninitialized value in numeric comparison (<=>) at -e line 1.
(1)(3) at -e line 1.
(3)(2) at -e line 1.
(3)(4) at -e line 1.
(nan)(inf) at -e line 1.
(inf)(nan) at -e line 1.
Use of uninitialized value $a in concatenation (.) or string at -e lin
+e 1.
()(nan) at -e line 1.
Use of uninitialized value in numeric comparison (<=>) at -e line 1.
Use of uninitialized value in concatenation (.) or string at -e line 1
+.
(nan)() at -e line 1.
Use of uninitialized value in numeric comparison (<=>) at -e line 1.
(nan)(1) at -e line 1.
(1)(nan) at -e line 1.
(1)(inf) at -e line 1.
(1)(inf) at -e line 1.
Use of uninitialized value $_ in print at -e line 1.
Use of uninitialized value $_ in print at -e line 1.
nannaninfinf1234
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I dont see how that can happen, except like

D:\>perl -e"print sort { $a <=> $b } undef, 1, undef, 2"
12
D:\>perl -e"print sort { $a <=> $b;undef } undef, 1, undef, 2"
Sort subroutine didn't return a numeric value at -e line 1.
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which is kind of stupid

Whatcha talkin bout Willis?

My nickname is tinita.
Go read the original posting.


perl -wle'@a = sort { print "$a <=> $b"; $a <=> $b } 2, 3, "nan";
print "\@a = @a";'
2 <=> 3
2 <=> nan
Sort subroutine didn't return a numeric value at -e line 1.
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So where's the last print statement? It isn't executed. sort dies. Or what exactly was your question?