$val部分
#!/usr/bin/envperl
use strict;
use warnings;
my $number = 3;
$number **= 3;
print "$number\n";
##27
print "lucky number is " , 8*11,".\n" ;
##lucky number is 88.
my $empty_number ;
print "This is a $empty_number\n";
##Use of uninitialized value $empty_number in concatenation (.) or string at test.pl line 22.
##This is a
my $apple = "apple";
#print "such $apple[]\n";
print "such $apple\[\]\n";
##Global symbol "@apple" requires explicit package name (did you forget to declare "my @apple"?) at test.pl line 29.syntax error at test.pl line 29, near "[]"
##such apple[]
#print "such $apple{}\n";
print "such $apple\{\}\n";
##Global symbol "%apple" requires explicit package name (did you forget to declare "my %apple"?) at test.pl line 33.syntax error at test.pl line 33, near "{}"
##such apple{}
print "such $apple::\n";
print "such $apple\:\:\n";
##Use of uninitialized value $apple:: in concatenation (.) or string at test.pl line 43.
##such
##such apple::
print "such $apple'\n";
print "such $apple\'\n";
##such apple'
##such apple'
my $big = "big";
print "I like $big $apples\n";
##Global symbol "$apples" requires explicit package name (did you forget to declare "my $apples"?) at test.pl line 60.
##Execution of test.pl aborted due to compilation errors.
print "I like $big ${apple}s\n";
print "I like $big" . " " . "$apple" . "s\n";
##I like big apples
##I like big apples
这里的apple::实际上是什么?
my $apple = "apple";
print "such $apple::\n";
print "such $apple\:\:\n";
##Use of uninitialized value $apple:: in concatenation (.) or string at test.pl line 43.
##such
##such apple::