更新数据和环路

Question

   $buy_amount = 50;     

       $amount[0] = 100; 
       $amount[1] = 150; 
       $amount[2] = 50; 

       $test; 

       $i = $buy_amount; 
       $arrlength = count($amount); 

       for ($x = 0; $x < $arrlength; $x++) { 

        $test = $amount[$x] - $i; 
        if ($amount[$x] != $test) { 
         $i = $test; 
         echo $test; 
         echo '<br/>'; 
        } 
       } 

我需要做的是，如果我发送$buy_amount = 50结果必须减去这样

例子：

$amount[0] = 50; 
    $amount[1] = 150; 
    $amount[2] = 50; 

如果我送$buy_amount = 150结果需减去这样

实施例：

  $amount[0] = 0; 
      $amount[1] = 100; 
      $amount[2] = 50; 

在这里我需要从第一个元素先做减法，去到其他和subtact从，如果buy_amount留下了去其他元素喜欢明智

Answer 1

我觉得这是你找什么

$amount[0] = 100; 
$amount[1] = 150; 
$amount[2] = 50; 

$buy_amount = 250; // Change to whatever you want 

$amount = array_map(
      function ($mValue) use (&$buy_amount) 
      { 

      if($buy_amount >= $mValue){ 

       $buy_amount = $buy_amount - $mValue; 
       return 0; 
      } 

      $sReturnValue = $mValue - $buy_amount; 
      $buy_amount = 0; 

      return $sReturnValue; 

      } 
      ,$amount); 

var_dump($amount);