[IMG]
lesson.png
 #7
~~~~~
 if...elseif...else
~~~~~
    if...elseif...else?    ?   ?         .
.  PHP  ,  ,     ,      .   #1.

 #1:
<?php
#  if_elseif_else.php
#    PHP

#  .  
$day = 21;
$month = '';

#  .  
if ($day == 22 && $month == '')
{
echo " !";
}
else
{
echo " !";
}

# 
?>
  ,     ?   .
    .   .  ...  ? -  ...  .   if...else (   a.    "...a    ".     $day  21, a  $month  "".    if...else    .     $day  21, a   $month  "",       " !", a    ,          ,    " !".
 PHP   :
$day = 21;
$month = '';

if ($day == 22 && $month == '')
{
echo " !";
}
else
{
echo " !";
}
  . 
   #2.
<?php
#  if_elseif_else2.php
#    PHP

#  .  
$count1 = 1;
$count2 = 99;
$total_count = $count1 + $count2;

#  .  
if ($total_count != 101)
{
echo "100";
}
else
{
echo $total_count;
}

# 
?>

       $count1  99,  $count2  1   $total_count   .   :    $total_count   101,      "100", a    ,       $total_count.
  #3:
<?php
#  if_elseif_else3.php
#    PHP

#  .  
$count1 = 1;
$count2 = 99;
$total_count = $count1 + $count2;

#  .  
if ($total_count == 200)
{
echo "200";
}
elseif ($total_count == 101)
{
echo "101";
}
else
{
echo $total_count;
}

# 
?>
   .
     $count1, $count2  $total_count.    :    $total_count  200,    .    $total_count  101,    .      ,      $total_count.
  :     100.
A   ,   :
1. if...else:
if ()
{
  ,   ,   
}
else
{
a   ,   ,   
}
2. if...elseif...else
if ()
{
  ,   ,   
}
elseif ()
{
  ,   ,    (elseif) 
}
else
{
a   ,   ,    
}

* .  elseif    
~~~~~
   ...       .