elseif, as its name suggests, is a combination
of if and else. Like
else, it extends an if
statement to execute a different statement in case the original
if expression evaluates to
false. However, unlike
else, it will execute that alternative
expression only if the elseif conditional
expression evaluates to true. For example, the
following code would display a is bigger than
b, a equal to b
or a is smaller than b:
<?php
if ($a > $b) {
echo "a is bigger than b";
} elseif ($a == $b) {
echo "a is equal to b";
} else {
echo "a is smaller than b";
}
?>
There may be several elseifs within the same
if statement. The first
elseif expression (if any) that evaluates to
true would be executed. In PHP, it's possible to write
else if (in two words) and the behavior would be identical
to the one of elseif (in a single word). The syntactic meaning
is slightly different (the same behavior as C) but the bottom line
is that both would result in exactly the same behavior.
The elseif statement is only executed if the
preceding if expression and any preceding
elseif expressions evaluated to
false, and the current
elseif expression evaluated to
true.
Note:
Note that elseif and else if
will only be considered exactly the same when using curly brackets
as in the above example. When using a colon to define
if/elseif conditions, the use
of elseif in a single word becomes necessary. PHP
will fail with a parse error if else if
is split into two words.
<?php
/* Incorrect Method: */
if ($a > $b):
echo $a." is greater than ".$b;
else if ($a == $b): // Will not compile.
echo "The above line causes a parse error.";
endif;
<?php
/* Correct Method: */
if ($a > $b):
echo $a." is greater than ".$b;
elseif ($a == $b): // Note the combination of the words.
echo $a." equals ".$b;
else:
echo $a." is neither greater than or equal to ".$b;
endif;
?>