May 28, 2023
A web crawler, also known as a web spider, is an automated program or script that systematically navigates through websites on the Internet to gather information. Web crawlers start by visiting a seed URL and then follow hyperlinks to other pages, recursively exploring and indexing the content they find.
The primary purpose of a web crawler is to gather data from web pages, such as text, images, links, metadata, and other relevant information. This collected data is typically used for various purposes, including web indexing, data mining, content scraping, and search engine optimization.
Web crawlers work by sending HTTP requests to web servers, downloading web pages, parsing the HTML or other structured data, and extracting relevant information. They follow the links found on each page to discover new URLs to crawl, creating a vast network of interconnected web pages.
You can get the complete code from Github:
index.php
“`html
parser(“https://www.algoberry.com”);
echo “
"; print_r($data); echo "
“;
?>
“`
config.php
“`html
“;
$outerHeadLength = strlen($outerHead);
$outerHeadStart = 0;
$innerHead = ““;
$innerHeadLength = strlen($innerHead);
$innerHeadStart = 0;
//–
//–
$outerTitle = “
$outerTitleLength = strlen($outerTitle);
$outerTitleStart = 0;
$innerTitle = “
$innerTitleLength = strlen($innerTitle);
$innerTitleStart = 0;
//–
//–
$outerMeta = ““;
$metaPointer = 0;
//–
//–
$metaNameBase = “name=”;
$metaNamePointer = 0;
//–
//–
$metaPropertyBase = “property=”;
$metaPropertyPointer = 0;
//–
//–
$metaContentBase = “content=”;
$metaContentPointer = 0;
//–
//–
$hrefTag = array();
$hrefTag[0] = ““;
$hrefTagCountStart = 0;
$hrefTagCountFinal = count($hrefTag);
$hrefTagLengthStart = 0;
$hrefTagLengthFinal = strlen($hrefTag[0]);
$hrefTagPointer =& $hrefTag[0];
//–
//–
$imgTag = array();
$imgTag[0] = ““;
$imgTagCountStart = 0;
$imgTagCountFinal = count($imgTag);
$imgTagLengthStart = 0;
$imgTagLengthFinal = strlen($imgTag[0]);
$imgTagPointer =& $imgTag[0];
//–
//–
$crawlOptions = array(
CURLOPT_RETURNTRANSFER => true, // return web page
CURLOPT_HEADER => false, // don’t return headers
CURLOPT_FOLLOWLOCATION => true, // follow redirects
CURLOPT_ENCODING => “”, // handle all encodings
CURLOPT_USERAGENT => “algoberrybot”, // who am i
CURLOPT_AUTOREFERER => true, // set referer on redirect
CURLOPT_CONNECTTIMEOUT => 10, // timeout on connect
CURLOPT_TIMEOUT => 10, // timeout on response
CURLOPT_MAXREDIRS => 0 // stop after 10 redirects
);
//–
?>
“`
WebCrawler.php