Question

<?php
    $customer = ["aa_","aa_","aa_","aa_"];
      $i = 0;
      do{
        $customer[$i] = $customer[$i].$i;
        $i++;
      } while ($i === 4);
      echo $i;   //print only 1
      var_dump($customer);  
    ?>

$customer实际输出

array (size=4)
      0 => string 'aa_0' (length=4)
      1 => string 'aa_' (length=4)
      2 => string 'aa_' (length=4)
      3 => string 'aa_' (length=4)

当我使用while ($i < 4)正在工作时。但在这里我误解了为什么使用about condition只能循环一次......我认为它应该是

   do $i++ -> 1  ( 1 === 4 ) loop again 
   do $i++ -> 2  ( 2 === 4 ) loop again 
   do $i++ -> 3  ( 3 === 4 ) loop again 
   do $i++ -> 4  ( 4 === 4 ) stop quit

所以预期$customer输出

array (size=4)
      0 => string 'aa_0' (length=4)
      1 => string 'aa_1' (length=4)
      2 => string 'aa_2' (length=4)
      3 => string 'aa_3' (length=4)

Answer 1

不，你的解释是错误的。

$i = 0 // Starting value
do (Will do the action here)  $i++ -> 1  
CONDITION ( 1 === 4 ) -> FALSE so it will not loop, (Stop the loop) so $i is only = 1;

如果你真的想在你的条件下使用equals，你应该使用!==（不等于），如下所示：

$i = 0;
do{
    $customer[$i] = $customer[$i].$i;
    $i++;
} while ($i !== 4);

所以解释是这个

$i = 0 // Starting value
do (Will do the action here)  $i++ -> 1  
CONDITION ( 1 !== 4 ) -> TRUE (Loop continues)
do (Will do the action here)  $i++ -> 2  
CONDITION ( 2 !== 4 ) -> TRUE (Loop continues)
do (Will do the action here)  $i++ -> 3  
CONDITION ( 3 !== 4 ) -> TRUE (Loop continues)
do (Will do the action here)  $i++ -> 4   
CONDITION ( 4 !== 4 ) -> FALSE (Stops the loop)
Final value of $i will be 4.

while循环不能像我在`===`状态中预期的那样工作吗？

1 个答案: