perl treat 0 false, non 0 ture.
print "false\n" if 0; print "false\n" if 0; ------------------------ ture
perl treat string empty is false.
my $temp = ""; print "This is $temp\n" if $temp; $temp = "HelloWorld"; print "This is $temp\n" if $temp; -------------------------------------------- This is HelloWorld
perl true/false,布布扣,bubuko.com
原文：http://www.cnblogs.com/peng-fei/p/3815848.html