my $var;
$var = 0;
$var = $var || 30;
print "1. var=$var\n";
$var = 0;
$var ||= 30;
print "2. var=$var\n";

##</code><code>##

1. var=30
2. var=30

##</code><code>##

int var = 0;
var = var || 30;
printf("1. var=%d\n", var);
// var ||= 30;     // oops, syntax error in C++

##</code><code>##

1. var=1