希望我能把它颠倒过来：PHP编程

This what I made.It become

              1
             121
            12321
           1234321

But I hope I can get

           1234321
            12321
             121
              1

I have tried so many times, but I can't make this. Anyone can help??

Do I make some mistake?

<?php
$p=4;
for($x=1;$x<=$p;$x++)
{
    for($q=$p;$q>$x;$q--)
    {
      echo "<center>";
    }
    for($k=1;$k<$x;$k++) 
    {
      echo $k;
    }
    if($x>=1) 
    {
        for($v=$x; $v>=1; $v--)
        {
           echo $v;
        }
    }      
echo "<br>";
}
?> 

I would appreciate it, if you can tell me my mistake. Thank You

You approach is correct, just minor update, Reverse the first for limits also, remove echo "<center>"; from inside the loop and place it outside

<?php
$p=4;
echo "<center>";
for($x=$p;$x>0;$x--)
{
    /* for($q=$p;$q>$x;$q--)
    {                                  //Not at all needed
      echo "<center>";
    } */
    for($k=1;$k<$x;$k++) 
    {
      echo $k;
    }
    if($x>=1) 
    {
        for($v=$x; $v>=1; $v--)
        {
           echo $v;
        }
    }      
echo "<br>";
}
echo "</center>";

Try this:

echo '<center>';
$p=4;
for($x=4;$x>0;$x--)
{

for($k=1;$k<$x;$k++) 
{
  echo $k;
}
if($x>=1) 
{
    for($v=$x; $v>=1; $v--)
    {
       echo $v;
    }
}    

echo "<br>";
}
echo '</center>';

Or an easier way:

$max = 4;

echo "<center>";
while ($max >= 1) {
    $string = '';
    for ($current = 1; $current <= $max; $current++) {
        $string .= $current;
    }
    echo $string . strrev(substr($string, 0, -1));
    echo '<br>';
    $max--;
}
echo "</center>";

This is the function you need:

function printCenterNb($nb, $html = true) {
    if ($html)
        echo '<center>';
    for($i = $nb; $i > 0; $i--) {
        for($i2 = 1; $i2 < $i; $i2++)
          echo $i2;
        for($i2 = $i; $i2>=1; $i2--)
           echo $i2;
        if ($html)
            echo "<br>";
    }
    if ($html)
        echo '</center>';
}

printCenterNb(5);