我正在尝试对数组中的数据运行清理作业,特别是将纪元时间转换为 YYYY-MM-DD.
我最初尝试过这个功能:
foreach ($data as $row) {$row['eventdate'] = date('Y-m-d', $row['eventdate']);}echo '';打印_r($数据);echo '</pre>';
但是,当我输出数据时,foreach 循环并没有更新数据.
以下 for 循环确实有效:
for ($i=0; $i
为什么第一个循环失败而第二个循环成功?他们不一样吗?
当您以目前的方式使用 foreach
循环时,foreach ($data as $row){
, $row
被按值"使用,而不是按引用".
尝试通过将 &
添加到 $row
来更新引用:
foreach ($data as &$row) {$row['eventdate'] = date('Y-m-d', $row['eventdate']);
或者,您可以使用键/值方法:
foreach ($data as $index => $row) {$data[$index]['eventdate'] = date('Y-m-d', $row['eventdate']);
I'm trying to run a clean up job on data in an array, specifically converting epoch time to YYYY-MM-DD.
I tried this function originally:
foreach ($data as $row) {
$row['eventdate'] = date('Y-m-d', $row['eventdate']);
}
echo '<pre>';
print_r($data);
echo '</pre>';
However the foreach loop didn't update the data when I output it.
The following for loop did work:
for ($i=0; $i<count($data); $i++) {
$data[$i]['eventdate'] = date('Y-m-d', $data[$i]['eventdate']);
}
Why did the first loop fail and the second work? Aren't they the same?
When you're using a foreach
loop in the way you currently are, foreach ($data as $row) {
, $row
is being used "by-value", not "by-reference".
Try updating to a reference by adding the &
to the $row
:
foreach ($data as &$row) {
$row['eventdate'] = date('Y-m-d', $row['eventdate']);
Or, you can use the key/value method:
foreach ($data as $index => $row) {
$data[$index]['eventdate'] = date('Y-m-d', $row['eventdate']);
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