Post-Module PHP Forms

Post-Module PHP Forms BTM 395: Internet Programming

Cookies • Cookie is a name-value pair stored on the user’s (client) computer • Track preferences and other information • Each server’s cookies stored as a text file on client computer • Stored securely so that it is difficult for other server-side applications to access another’s cookies • But don’t store sensitive information (e.g. credit card number) without encryption • Security risk if someone has physical access to the user’s computer • Write or change cookies: • setcookie( $name, $value ); various optional options (e.g. expiration date) • Read cookies • Use the $_COOKIE['name'] environment variable

Sessions • A session is a built-in way of tracking a user across multiple pages • Implemented using cookies • Thus, requires cookies to be enabled on client side

PHP string quoting • ' (single quote): for literal strings with minimal text expansion (\\ and \' only) • " (double quote): for flexible strings with expansion of variables and many codes (e.g. \n and \t) • Heredoc: for lengthy strings with complex plain-text format (see http://codepad.org/pzHHK3wH) • Begins with <<<ANY_DELIMITER • Ends with ANY_DELIMITER; as the only contents of closing line • Expands variables similarly to " • Nowdocformat works like single quote equivalent of heredoc • Official reference: http://php.net/manual/en/language.types.string.php

Array indexing • ALL arrays in PHP are associative arrays • Numeric indices are automatically generated, but the arrays are still fully associative • Arrays can have both flexible associative keys and auto-generated numeric keys • Official reference: http://www.php.net/manual/en/language.types.array.php

Customized array sorting • PHP has many built in array sort functions, for sorting by value, by key, and backwards • JavaScript only has one very limited built-in sort: lexicographic (strict alphabetic) sort • Both have custom sort functions that work similarly • JavaScript: myArray.sort(function(a,b){…}); • PHP: usort($myArray,customSortFunction);customSortFunction(a,b){…}; • These can sort any kind of array anyway you like, including multidimensional arrays

Other PHP tips • Equality and assignment = vs == vs === • The ternary (conditional) operator ? : • $myVar = $testCondition? $valueIfTrue: $valueIfFalse; • Ternary operator exercise • Stop an infinite loop in PHP • Click the stop or cancel button on your browser to stop the page loading • Or just wait 30 seconds or so for a server timeout

Sources • Heredoc example: http://www.tuxradar.com/practicalphp/2/6/3

Post-Module PHP Forms