`else`

Often you'd want to execute a statement if a certain condition is met, and a different statement if the condition is not met. This is what else is for. else extends an if statement to execute a statement in case the expression in the if statement evaluates to FALSE. For example, the following code would display a is bigger than b if $a is bigger than $b, and a is NOT bigger than b otherwise:


<?php

if ($a > $b) {

    echo "a is bigger than b";

} else {

    echo "a is NOT bigger than b";

}

?>

The else statement is only executed if the if expression evaluated to FALSE, and if there were any elseif expressions - only if they evaluated to FALSE as well (see elseif).

User Contributed Notes
else

jak at mNuOnSkPeAeMs dot co dot uk
16-Mar-2005 04:42


Surely it should print "messages" for all values except 1. i.e. You have 0 messages, You have 1 message, You have 2 messages.

So wouldn't this be the easy answer...?



<?php

echo "You have $i message".($i!=1?"s":"")." in your mailbox.\n";

?>

15-Dec-2004 09:41


cgeng, the negative value is intentional:



echo "You have $i message".($i-1?"s":"")." in your mailbox.\n";



With one and only one message, this prints "You have 1 message in your mailbox." With any and all other values, it prints "You have # messages in your mailbox." This is grammatically correct for all values of $i.

cgeng at home dot se
09-Dec-2004 06:46


Stephens example is an example of tersity taken too far:



echo "You have $i message".($i-1?"s":"")." in your mailbox.\n";



gives a negative value of the expression if there are no messages, which, if defined, should be interpreted as false.

Caliban Darklock
08-Nov-2004 01:24


If you're coming from another language that does not have the "elseif" construct (e.g. C++), it's important to recognise that "else if" is a nested language construct and "elseif" is a linear language construct; they may be compared in performance to a recursive loop as opposed to an iterative loop. 



<?php

$limit=1000;

for($idx=0;$idx<$limit;$idx++)  

{ $list[]="if(false) echo \"$idx;\n\"; else"; }

$list[]=" echo \"$idx\n\";";

$space=implode(" ",$list);| // if ... else if ... else

$nospace=implode("",$list); // if ... elseif ... else

$start=array_sum(explode(" ",microtime()));

eval($space);

$end=array_sum(explode(" ",microtime()));

echo $end-$start . " seconds\n";

$start=array_sum(explode(" ",microtime()));

eval($nospace);

$end=array_sum(explode(" ",microtime()));

echo $end-$start . " seconds\n";

?>



This test should show that "elseif" executes in roughly two-thirds the time of "else if". (Increasing $limit will also eventually cause a parser stack overflow error, but the level where this happens is ridiculous in real world terms. Nobody normally nests if() blocks to more than a thousand levels unless they're trying to break things, which is a whole different problem.)



There is still a need for "else if", as you may have additional code to be executed unconditionally at some rung of the ladder; an "else if" construction allows this unconditional code to be elegantly inserted before or after the entire rest of the process. Consider the following elseif() ladder:



<?php

if($a) { conditional1(); }

elseif($b) { conditional2(); }

elseif($c) { conditional3(); }

elseif($d) { conditional4(); }

elseif($e) { conditional5(); }

elseif($f) { conditional6(); }

elseif($g) { conditional7(); }

elseif($h) { conditional8(); }

else { conditional9(); }

?>



To insert unconditional preprocessing code for $e onward, one need only split the "elseif":



<?php

if($a) { conditional1(); }

elseif($b) { conditional2(); }

elseif($c) { conditional3(); }

elseif($d) { conditional4(); }

else {

....unconditional();

....if($e) { conditional5(); }

....elseif($f) { conditional6(); }

....elseif($g) { conditional7(); }

....elseif($h) { conditional8(); }

....else { conditional9(); }

}

?>



The alternative is to duplicate the unconditional code throughout the construct.

stephen at dotnetbytes dot com
29-Oct-2004 11:32


me, being a c/c++ programer, would be lazy and try to type as few characters as possible so that last statement:

echo "You have $i ". ($i==1 ? "message" : "messages"). " in your mailbox.\n"; 



can become:

echo "You have $i message".($i-1?"s":"")." in your mailbox.\n";



since if $i is 1 it ($i-1) would result in a 0 and evaluate as false. But if $i is more than 1 will be a positive integer and evaluate as true and add the 's'.

cap at capsi dot com
06-Oct-2000 12:58


Often you can avoid large if/else statements in your code by using the ternary operator. For example:





<?php


echo "You have $i ". ($i==1 ? "message" : "messages"). " in your mailbox.\n";


?>