同时为什么在这种情况下价值会发生变化？

Question

when you try this code the result is ... The number is 1

<?php
$i=1;
do
  {

  echo "The number is " . $i . "<br />";
    $i++;

  }
while ($i==10);
?>

but when you change this code to be like this the result is 2

<?php
$i=1;
do
  {

    $i++;
      echo "The number is " . $i . "<br />";


  }
while ($i==10);
?>

so why the result changed ..?

Answer 1

$i++; is post increment operator so it will increment value by 1 on next line and it use same value on current line

First Case: you are doing echo $i and then doing increment

Second Case: you are incrementing $i++ before echo statement so by nature it will increase value by 1 on echo line