Hello again,

I was playing with 'do{ }' and found interesting behaviour. Here is a code:

#!/usr/bin/perl -l

use strict;
use warnings;

my $uninitialized;

print do { $uninitialized };
print do {};
print do { if( 1 ){} };
print do { if( 0 ){} };

print '-' x 10;

print scalar do { $uninitialized };
print scalar do {};
print scalar do { if( 1 ){} };
print scalar do { if( 0 ){} };
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output:

Use of uninitialized value $uninitialized in print at ./perlmonks_do_u
+nitialized.pl line 8.



0
----------
Use of uninitialized value $uninitialized in print at ./perlmonks_do_u
+nitialized.pl line 15.

Use of uninitialized value in print at ./perlmonks_do_unitialized.pl l
+ine 16.

Use of uninitialized value in print at ./perlmonks_do_unitialized.pl l
+ine 17.

0
[download]

For me it is strange that 'scalar do {};' and 'scalar do { if( 0 ){} };' have different outputs, as the codes look equivalent. Can someone explain a difference in the output?