간과하기 쉬운 작은 실수, 혹시 해보신 적 있으신가요?

foreach 数组 值修改

/**
 * 注意foreach取值的差异
 */
$arr = array(1,2,3,4);

echo "foreach遍历数组1：";
foreach($arr as $val) {
    $val = $val*2;
}

var_dump($arr);

echo "foreach遍历数组2：";
foreach($arr as &$val) {
    $val = $val*2;
}

var_dump($arr);
/*end of php*/