Zend Studio报告警告：分配情况。这样不好吗 [英] Zend Studio reports warning: Assignment in condition. Is this so bad?

问题描述

我最近开始使用Zend Studio，它已警告以下类型的代码：

I have recently started using Zend Studio which has reported as warning the following type of code:

$q = query("select * from some_table where some_condition");
while ($f = fetch($q)) {
  // some inner workings
}

要停止警告，需要这样编写代码：

To stop the warning the code needs to be written like this:

$q = query("select * from some_table where some_condition");
$f = fetch($q);
while ($f) {
  // some inner workings
  $f = fetch($q);
}

为什么将此标记为警告？

Why is this marked as a warning? Is it so bad?

我了解该警告可能旨在阻止此类错误：

I understand that the warning may be designed to stop errors like this:

$a = 1;
while ($a = 1) {
  // some inner workings
  $a++;
}

永远不会终止，因为将1分配给$ a会返回while语句为1，而不是针对$ a进行测试，并且在$ a不为1的情况下向while语句返回false。

which will never terminate because 1 is being assigned to $a which in turn returns 1 to the while statement, rather than being tested against $a and returning false to the while statement when $a is not 1.

容易出错，可以验证a警告，虽然可以，但是却忘记了在第二个示例的while块的末尾添加额外的$ f = fetch（$ q），这也将导致循环永远不会终止。如果我更改代码以删除警告，然后忘记在while块的末尾添加$ f = fetch（$ q），则Zend不会发出警告！

Easy error to make which may validate a warning, granted, but so is forgetting to add the extra $f = fetch($q) at the end of the while block in the second example which will also result in a loop that will never terminate. If I change my code to remove the warning and then forget to add the $f = fetch($q) at the end of the while block Zend won't warning be about that!

因此，通过删除有关常见错误的警告，我将自己设置为其他常见错误。

So by removing the warning concerning a common error I'm setting myself up for a different common error.

出锅，入火。

推荐答案

while (($row = $sql->db_Fetch("MYSQL_ASSOC")) != false)

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