  php  (if, else, elseif), , 
(while, do-while, for, foreach, break, continue), 
  (switch) switch       if, 
     ,   3    if. 
  (declare),    (return), 
  (require, include).

  :

<?php
$q=1;
$w=1;
if($q=$w)
{
    print "$q  $w";
}
else
{
    print "$q   $w";
}
exit;
?>

        " $q  1, 
 $w  1,   q   w      q  
 w,                
  ".

<?php
$q=2;
$w=3;
if($q>$w)
{
    print "$q  $w";
}
elseif($q=$w)
{
    print "$q  $w";
}
else
exit;
?>

    "elseif"     "if"  , 
  (if)    -     - ,      - (elseif), 
      -   - ,        :)    
 :  (if)   :   $q   $w    : "$q  $w", 
  elseif -   if  (false)      $q   $w       $q  $w, 
      "$q  $w",    (else)   .

<?php
$q=0;
while($q<10)
{
    $q++;
    print $q;
}
?>

    , 
       1,  2    10,  "12345678910". 
   " (  ..) 
    ,   $q    10, 
      , 
       1 "$q++"      ".