PHP is a powerful open source server-sided scripting language that can be used on a wide variety of operating systems and webservers, including Apache on UNIX and IIS on Windows.
PHP contains numerous extensions which enable you to dynamically create images and flash files, parse xml, connect to remote servers using pop, imap, ftp, http and raw sockets, natively access many database servers including PostgreSql, MySQL and Microsoft SQL Server, compress and decompress files, lookup domain names and and much more.
PHP has an excellent manual and online documentation which covers every function for every extension available.
It’s easy to get the filename and directory name components of a full path name with PHP using the dirname(), basename() and pathinfo() functions. The latter also contains the filename extension.
PHP has heredoc syntax like other programming languages to interpolate variables into large string blocks (which I’ve covered in an earlier post). In PHP 5.3.0 a new string delimiter was introduced called "nowdoc" which works in the same was as heredoc but acts like a single quoted string, so no variable interpolation or parsing is done.
When scraping content using the PHP Simple HTML DOM Parser it is useful to resolve relative URLs in a page to absolute URLs for downloading additional web pages or images. I do this using the url_to_absolute library byNadeau Software Consulting and show how to do this here, along with a minor fix which needs to be done to their code.
This post shows how to download a web page and find all the link anchor tags in the page using PHP and the Simple HTML DOM Parser which has a jQuery like syntax selector.
Objects in PHP are assigned by reference, so copying an object with the = operator will result in a second variable referencing the same object and not an actual copy. Enter PHP’s clone function which creates a shallow copy of the object.
A little while back I posted how to extract the domain, path, etc from a url with PHP and in this follow up post show how to extract the query string into an associative array using the parse_str function.