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Helping ordinary people create extraordinary websites! |
Writing PHPBy Neil Williams2007-11-11 
PHP and HTTP: headers and variables
PHP files can contain a mixture of code and you can insert php code anywhere in the document. Code sections begin with <?php or <script language="php" Some PHP installations will allow a shortened tag <? but this will clash with any XML or WML output so check your phpinfo output for "short_open_tag off" before trying XML and PHP. HTML, XML and WML code can be entered as a PHP variable using $variable="my content" If the content includes text quotes (e.g. tag attributes), use the backslash to "escape" the quotation marks - \" e.g. $html_output="<html> <body> The Header function can be used to output formats other than the default HTML. For WML use the PHP command: Header("Content-type:text/vnd.wap.wml");Only set the Header once for each possible non-HTML output of the PHP file. Duplicate Header assignments will generate PHP parsing errors. HTTP header information is always available in all PHP files - for a full list see the phpinfo output - so detecting the browser USER_AGENT setting is straighforward: $agent = getenv("HTTP_USER_AGENT");To check for a match with Internet Explorer 5, use a Perl type regular expression: if (preg_match("/MSIE 5/i", "$agent")) {echo ("$ie5");exit;}Detect WML browsers (like WAP phones) through the use of getenv("HTTP_ACCEPT"). WML browsers set this value to text/vnd.wap.wml - amongst other settings. Tutorial Pages: » What can PHP do? » PHP output » PHP and HTTP: headers and variables » No need for CGI access » Preventing and solving bugs in PHP » Checking user input for dubious or erroneous values » Read remote files, read and write local files on the server » Common PHP functions » Building, sorting, reversing and flipping arrays » Current time, date calculations, timestamp formats » PHP string functions Copyright © Neil Williams
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