my $x = 2;
print "\$x is '$x'\n";

if ( $x = 0 ) {
    print "\$x = 0 is true\n";
}
else {
    print "\$x = 0 is false\n";
}

print "\$x is '$x'\n";
__END__
$x is '2'
$x = 0 is false
$x is '0'