Conseguir url de la primera imagen de la página actual

[fbedia]

Hice este pequeño script que espero que te sirva:

Código PHP:

<?php 
//guardo en $content el codigo fuente de la web que quiero extraer las imagenes
$content=implode('',file('http://www.forosdelweb.com/f18/conseguir-url-primera-imagen-pagina-actual-1117890/')); 
//la expresion regular a usar... puedes refinarla a tu antojo
$expresion= '@src="([^"]+)"@';
//saco las coincidencias a un array
preg_match_all($expresion,$content,$considencias);
//pinto el array
print_r($considencias);
?>
 

Este script basicamente lo que hace es recorrer el codigo fuente y extraer los "src="
Puedes cambiar la expresion regular a tu antojo para que solo coja desde el http y dentro de un tag <img
A mi se me dan mal las expresiones regulares, por lo que para el ejemplo lo he apañado de esta forma...

Una vez tengas el array con todas las imagenes, puedes sacar la imagen de la posicion que quieras: primera, 5º, ultima..etc....

El resultado de lo anterior es el siguiente:

Array ( [0] => Array ( [0] => src="http://ajax.googleapis.com/ajax/libs/yui/2.9.0/build/yahoo-dom-event/yahoo-dom-event.js?v=387" [1] => src="http://ajax.googleapis.com/ajax/libs/yui/2.9.0/build/connection/connection-min.js?v=387" [2] => src="http://static.forosdelweb.com/clientscript/vbulletin_global.js?v=387" [3] => src="http://static.forosdelweb.com/clientscript/fdw_menu.js?v=1" [4] => src="http://static.forosdelweb.com/clientscript/fdw_header.js?v=1" [5] => src="http://static.forosdelweb.com/clientscript/vbulletin_post_loader.js?v=387" [6] => src="http://static.forosdelweb.com/images/misc/unknown.gif" [7] => src="http://static.forosdelweb.com/clientscript/vbulletin_ajax_tagsugg.js?v=387" [8] => src="http://static.forosdelweb.com/clientscript/fdw_ajax_tagsugg.js?v=387" [9] => src="http://static.forosdelweb.com/clientscript/fdw_ajax_eval.js" [10] => src="http://static.forosdelweb.com/fdwtheme/images/statusicon/post_old.gif" [11] => src="http://static.forosdelweb.com/fdwtheme/images/smilies/afirmar.gif" [12] => src="http://static.forosdelweb.com/fdwtheme/images/statusicon/post_old.gif" [13] => src="http://static.forosdelweb.com/customavatars/avatar445885_1.gif" [14] => src="http://static.forosdelweb.com/images/misc/11x11progress.gif" [15] => src="http://static.forosdelweb.com/clientscript/vbulletin_ajax_taglist.js?v=387" [16] => src="http://static.forosdelweb.com/clientscript/vbulletin_ajax_tagsugg.js?v=387" [17] => src="http://static.forosdelweb.com/fdwtheme/images/buttons/reply.gif" [18] => src="http://static.forosdelweb.com/clientscript/vbulletin_facebook.js?v=102" [19] => src="http://connect.facebook.net/es_LA/all.js" [20] => src="http://static.forosdelweb.com/images/misc/facebook_login.gif" ) [1] => Array ( [0] => http://ajax.googleapis.com/ajax/libs...event.js?v=387 [1] => http://ajax.googleapis.com/ajax/libs...n-min.js?v=387 [2] => http://static.forosdelweb.com/client...lobal.js?v=387 [3] => http://static.forosdelweb.com/client...dw_menu.js?v=1 [4] => http://static.forosdelweb.com/client..._header.js?v=1 [5] => http://static.forosdelweb.com/client...oader.js?v=387 [6] => http://static.forosdelweb.com/images/misc/unknown.gif [7] => http://static.forosdelweb.com/client...gsugg.js?v=387 [8] => http://static.forosdelweb.com/client...gsugg.js?v=387 [9] => http://static.forosdelweb.com/client...w_ajax_eval.js [10] => http://static.forosdelweb.com/fdwthe...n/post_old.gif [11] => http://static.forosdelweb.com/fdwthe...es/afirmar.gif [12] => http://static.forosdelweb.com/fdwthe...n/post_old.gif [13] => http://static.forosdelweb.com/custom...ar445885_1.gif [14] => http://static.forosdelweb.com/images...11progress.gif [15] => http://static.forosdelweb.com/client...glist.js?v=387 [16] => http://static.forosdelweb.com/client...gsugg.js?v=387 [17] => http://static.forosdelweb.com/fdwthe...tons/reply.gif [18] => http://static.forosdelweb.com/client...ebook.js?v=102 [19] => http://connect.facebook.net/es_LA/all.js [20] => http://static.forosdelweb.com/images...book_login.gif ) )