`elseif`

elseif, como su nombre sugiere, es una combinaciÃ³n de if y else. Como else, extiende una sentencia if para ejecutar una sentencia diferente en caso de que la expresiÃ³n if original se evalÃºa como FALSE. No obstante, a diferencia de else, ejecutarÃ¡ esa expresiÃ³n alternativa solamente si la expresiÃ³n condicional elseif se evalÃºa como TRUE. Por ejemplo, el siguiente cÃ³digo mostrarÃa a es mayor que b, a es igual a b o a es menor que b:


<?php

 if ($a > $b) {

     print "a es mayor que b";

 } elseif ($a == $b) {

     print "a es igual que b";

 } else {

     print "a es mayor que b";

 }

?>

Puede haber varios elseifs dentro de la misma sentencia if. La primera expresiÃ³n elseif (si hay alguna) que se evalÃºe como TRUE se ejecutarÃa. En PHP, tambiÃ©n se puede escribir 'else if' (con dos palabras) y el comportamiento serÃa idÃ©ntico al de un 'elseif' (una sola palabra). El significado sintÃ¡ctico es ligeramente distinto (si estas familiarizado con C, es el mismo comportamiento) pero la lÃnea bÃ¡sica es que ambos resultarÃan tener exactamente el mismo comportamiento.

La sentencia elseif se ejecuta sÃ³lo si la expresiÃ³n if precedente y cualquier expresiÃ³n elseif precedente se evalÃºan como FALSE, y la expresiÃ³n elseif actual se evalÃºa como TRUE.

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elseif

jsimlo
15-Aug-2006 07:02


This example generates a parse error:

<?

if ($a==1):

 /* nested if */

 if ($b==1) echo "2";

elseif ($a==3):

 /* other code */

endif;

?>



The nested "if" binds to the outer "elseif" and the colon the generates an error: syntax error, unexpected ':'.



According to http://bugs.php.net/bug.php?id=838 this "bug" is not going to be fixed. Beware.



An "artful" sollution to this bug could look like this:



<?

if ($a==1):

 /* nested if */

 if ($b==1) echo "2";

 /* dummy expression */

 ;

elseif ($a==3):

 /* other code */

endif;

?>

phpprogrammer at artspad dot net
10-Aug-2006 10:58


The comment critizing matheo's code while making some perhaps interesting statements about code efficiency missed the point completely.



echo 0; is different then echo false;

echo 0 will print a 0

echo false will print nothing.



So, the ternary operator technique was simply assuring there would be a displayable value.



If anything matheo showed prowess as a programmer and that he was knowledgable about nuances in php programming by knowing how to use the ternary operator to provide values true and false that are displayable.



Perhaps a clearer example of this would have been:

$is_a_bigger = ($a > $b) ? "true" : "false" ;



It is true that the result of a logic expression is a value like any other, it is a value though of a specific type which if using === can be checked for boolean logic which may or may not be what a programmer wants.



The general caveat if we are going to pontificate to programmers is to know exacly what you are getting from any operation and know the consequences of doing so. Which I think matheo knew quite well, and appropriately accounted for.

mega0m3ga at yahoo dot com
09-Apr-2005 08:44


Dont make your code as jumbled up as this:



if (!$username || !$password) {

    echo("<form method='post' action='signin.php'>");

} elseif($action == "c" || $action == "d" || $action == "e" || $action == "f" || $action == "g" || $action == "h" || $action == "i") {

    echo("<form method='post' action='" . findbattle() . ".php'><input type='hidden' name='strt' value='y'>");

} elseif($action == "b") {

    die ("Sorry, dude. You're banned from this site!");

} else {

    echo("<form method='post' action='game.php'>");

}



It works best when you only compare related variables.

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MANUAL DE PHP

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`elseif`