笔试汇总（php，mysql..）

$a = “aabbzz”;
$a++;
echo $a;//aabcaa

$arr = [1,2,3,4];
foreach ($arr as &$item) {
echo $item;
}
print_r($arr);
foreach ($arr as $item) {
echo $item;
}print_r($arr);
echo implode(‘,’,$arr);
//1233