From what I can see you've missed out the "endwhile;" statement, and you've forgotten to auto increase $i
Try:
PHP Code:
$reset_0[0]==="aaa";
$reset_0[1]==="bbb";
$reset_0[2]=="111";
$reset_0[3]=="222";
$i = 0;
while ($i <= 18) :
if($reset_0[$i]===a){$reset_1[$i]="933"; echo $reset_1[$i];}
if($reset_0[$i]===A){$reset_1[$i]="588";}
if($reset_0[$i]===b){$reset_1[$i]="811";}
if($reset_0[$i]===B){$reset_1[$i]="433";}
if( empty($reset_0[$i])){$reset_1[$i]="";}
$i++;
endwhile;
echo $reset_1[0];
echo $reset_1[1];
echo $reset_1[2];
echo $reset_1[3];