php数组：如何在关联数组中访问“$ key-1”？

Question

我有一套带有一系列条件的现有foreach，我想保持原样并添加结束日期，这是该行开始日期之前+一天

我怎样才能访问“$ line-1”来执行：

foreach($tab as $line){
       if the line before with $line[beginning_date] exists
           $line[end_date]=   the line before with $line[beginning_date] value +1
 }

Answer 1

够好吗？

$theLineBefore = null;
foreach($tab as $line){
       if the line before with $line[beginning_date] exists
           $line[end_date]=   the line before with $line[beginning_date] value +1
  $theLineBefore = $line;
 }