PHP var_dump和循环给出不同的结果 [英] PHP var_dump and loop giving different results

问题描述

  var_dump（$ cursor）; 
 foreach（$ cursor为$ obj）{
 echo< div class ='item'id ='。 $ obj ['_ id']。 >中; 
 echo< span class ='listnick'> 。 $ obj ['nick']。 < /跨度> 中; 
回显< / div>; 
 
 code $ 
 
 
 
 var_dump的结果如下：
 
 
  array（2）{
 [0] => 
& array（9）{
 [_id] => 
 object（MongoId）＃9（1）{
 [$ id] => 
 string（24）50af8dcd9cc231534400000c
} 
 
 [nick] => 
 string（6）safari
 
} 
 [1] => 
 array（9）{
 [_id] => 
 object（MongoId）＃8（1）{
 [$ id] => 
 string（24）50af8dca9cc2315644000009
} 
 [nick] => 
 string（6）chrome
} 
} 
  
所以显然这个foreach应该打印出safari和chrome，但是这个问题真的很奇怪：
 
有时它会返回两次Safari并且省略chrome反之亦然。我试着把var_dump和foreach循环放在附近，以确保它们是相同的，并且两个命令之间的对象没有变化，但是我真的不知道发生了什么。
 
 
 
有什么帮助？提前感谢。
解决方案
 注意safari是如何引用数组的：& array。 b 
 
这可能是由于有一个foreach，其中$ obj是一个引用：
 
 
  foreach（$ cursor as& $ obj）{
 .. 
} 
 // unset（$ obj）; 
  
在PHP中，$ obj的作用域并不以循环的执行结束，因此您应该
 
 
这也可能是因为在某处使用了引用赋值：
 
 
  $ cursor [] =& $野生动物园; 
  
 
I have the following code:
var_dump($cursor);
foreach($cursor as $obj) {
    echo "<div class='item' id='" . $obj['_id'] . "'>";
        echo "<span class='listnick'>" . $obj['nick'] . "</span>";
    echo "</div>";
}
The result of var_dump is the following:
array(2) {
  [0]=>
  &array(9) {
    ["_id"]=>
    object(MongoId)#9 (1) {
      ["$id"]=>
      string(24) "50af8dcd9cc231534400000c"
    }

    ["nick"]=>
    string(6) "safari"

  }
  [1]=>
  array(9) {
    ["_id"]=>
    object(MongoId)#8 (1) {
      ["$id"]=>
      string(24) "50af8dca9cc2315644000009"
    }
    ["nick"]=>
    string(6) "chrome"
  }
}
so obviously the foreach should print out "safari" and "chrome", but the problem is really weird:


Sometimes it returns "safari" twice and omits "chrome", and viceversa for the other client. I tried putting the var_dump and the foreach loop near to be sure they are the SAME and there are no changes in the object between the two commands, but really I got no idea what's going on.

Any help? Thanks in advance.
解决方案
Notice how safari is a reference to an array: &array.

This might result from having a foreach where $obj is a reference:
foreach($cursor as &$obj) {
   ..
}
//unset($obj);
In PHP, the scope of $obj does not end with execution of the loop, so you should do an unset whenever you looped using a reference.

This might also result from using the reference assignment somewhere:
$cursor[] =& $safari;


                        
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