如果 a 等于 b，则打印“1”，如果 a 大于 b，则打印“2”，否则打印“3”。
Output "1" if $a is equal to $b,
print "2" if $a is greater than $b,
otherwise output "No".
$a = 50;
$b = 10;
@(2) ($a == $b) {
echo "1";
} @(6) ($a > $b) {
echo "2";
} @(4) {
echo "3";
}
$a = 50;
$b = 10;
if ($a == $b) {
echo "1";
} elseif ($a > $b) {
echo "2";
} else {
echo "3";
}