Resizing images Web applications often need to work with images like pictures of users or photos etc. So the need to need to resize images comes up when creating thumbnails for example or compressing images for storage. The default library to handle image operations in php is GD. It can be used to resize images…. Read More »
If using this code <IfModule mod_php5.c> #Turn off php register globals php_flag register_globals off </IfModule> gives the error : .htaccess: php_flag not allowed here in /var/log/apache/error.log Then Options should be added to AllowOverride in : /etc/apache2/sites-available/default AllowOverride FileInfo Options like this <Directory /var/www/> Options Indexes FollowSymLinks MultiViews AllowOverride FileInfo Options Order allow,deny allow from all… Read More »
System load System load is a measure of how busy the system is running the processes. Higher system load simply means more processes are running and more are waiting to be run. When coding php applications, it sometimes is useful or necessary to find the current load on the server/system. For example if you want… Read More »
To go back to the previous page the superglobal variable $_SERVER can be used. $_SERVER[‘HTTP_REFERER’] has the link to the previous page. So to redirect simply : #Method to go to previous page function goback() { header("Location: {$_SERVER['HTTP_REFERER']}"); exit; } goback();
The numerical system used in India differs from the Western system in terms of the placement of the thousands separator. Example : Number -> 1000000 Indian System -> 10,00,000 (Ten Lakh) Western System -> 1,000,000 (1 Million) While echoing numbers in PHP it is possible to format numbers with such separators using functions like number_format…. Read More »
Ip to Location Many applications need to get information about the geographical location of the user/visitor on their websites. This can be done in many ways. There are online services like ipinfodb and geoio that provide web based api to get the geolocation information about a given ip address. Services like Maxmind geoip provide free… Read More »
Parsing dates Most php applications need to parse dates and convert them to timestamps for example. Parsing is also necessary to convert the date into a more standard format like yyyy-mm-dd which can be stored in a database like mysql. Mysql database stores dates in the format yyyy-mm-dd like 2009-04-15. However humans are more used… Read More »
In a previous post we learnt how to inside php. In this example the same zip file would be used to restore the database. Code // Function to restore from a file function restore($path) { $f = fopen('restore/temp.sql' , 'w+'); if(!$f) { echo "Error While Restoring Database"; return; } $zip = new ZipArchive(); if ($zip->open($path)… Read More »
Many php applications prefer to backup the mysql database from within the application and save it as an archive. The mysqldump commandline utility can be used to perform this function of backing up a mysql database as sql file. The command would be like this : mysqldump –user=$username –password=$password –opt $db_name > $dir/backup.sql The above… Read More »
The following function will parse a given text and convert all the urls into links. It does this using regular expressions. It converts email addresses to mailto links as well. Code function parse_links($str) { $str = str_replace('www.', 'http://www.', $str); $str = preg_replace('|http://([a-zA-Z0-9-./]+)|', '<a href="http://$1">$1</a>', $str); $str = preg_replace('/(([a-z0-9+_-]+)(.[a-z0-9+_-]+)*@([a-z0-9-]+.)+[a-z]{2,6})/', '<a href="mailto:$1">$1</a>', $str); return $str; }