dousi4950 2014-11-26 05:42
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PHP数组引用,修改数组值

I'm trying to modify an array when looping through it and increment certain values.

     $data = ['traits' => [[['amt' => 1]]]];
     var_dump($data['traits']);

      foreach ($data['traits'] as $key => &$index) {

        foreach ($index as $key => &$value) {

          $value['amt'] = $value['amt']++; // This should increment

          if (in_array($key, $input)) {
            $i++;
            $insert["field_".$i] = $key."_1";
          }
        }
      }

      var_dump($data['traits']);    // SAME AS PREVIOUS VAR_DUMP
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1条回答 默认 最新

  • douyanzhou1450 2014-11-26 06:19
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    What you are doing in the loop is undefined:

    $value['amt'] = $value['amt']++;
    

    The outcome of that depends on what's evaluated first. In this case $value['amt']++ seems to be evaluated first and then assigned to $value['amt'] again; the side effect of the increment is lost.

    On the other hand, the following statement will work as expected:

    $value['amt']++;
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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