This is a simple technique to extract the filename extension from a filename. It could easily be adapted to extract the filename from a path or a query string from a URL by changing the first parameter of the explode() function.
$extension = end(explode('.', $filename)); |
Here's a useful function to strip the extension off of a filename.
if($ext !== false) { $name = substr($name, 0, -strlen($ext)); } return $name; |
It's easy to overlook security when we write PHP code, yet failure to write code with security in mind can result in catastrophe.
Rather than write the book myself, this is one of those cases where we should just reference some good material written by others.
IP addresses can't readily be sorted numerically because they are strings and the periods in the dotted-quad format common to IP addresses confuses things. For instance, in a sorted list, 143.16.20.11 will sort before 23.45.1.78 even though what you really want is to sort by the first octet (23 & 143), then by the second octed (16 & 45) and so on.
PHP and MySQL provide functions to convert IP addresses to sortable format.
Two functions are provided for use in MySQL query. When your IP addresses are stored in a database, you can pull them ready to sort.
INET_ATON() Returns the numeric value of an IP address
INET_NTOA() Returns the IP address converted from a numeric value
Remember that if you need both representations you can pull the value twice in the same query, i.e.
SELECT ip AS ip_dotted_quat,INET_ATON(ip) as ip_sortable FROM mytable
This provides a clean set of data for your PHP or other scripting code to work with.
You have similar options in PHP.
ip2long("127.0.0.1") converts the IP to a long integer.
long2ip() converts the long integer back to a dotted-quad IP address.
The online PHP manual suggests using the two in combination to validate an IP as shown here
<?php
// make sure IPs are valid. also converts a non-complete IP into
// a proper dotted quad as explained below.
$ip = long2ip(ip2long("127.0.0.1")); //Â "127.0.0.1"
$ip = long2ip(ip2long("10.0.0")); //Â "10.0.0.0"
$ip = long2ip(ip2long("10.0.256")); //Â "10.0.1.0"
?> When you read a row from your dataset and want to work with it, like building table rows, it can be hard to write, debug and maintain your code using the conventional syntax that requires you to move in and out of a quoted string, inserting elements from the row array like this;
while ($row = mysql_fetch_assoc($result)) {
// work with the data from your row
echo "<tr><td>".row['name']."</td><td>".row['address']."</td></tr>";
}
It's a lot easier to do this if you convert your row elements to simple variables which can be placed directly in the quoted string, like this;
[sourcecode language="php"]
while ($row = mysql_fetch_assoc($result)) {
// create a variable for each attribute
foreach($row as $var => $value){
$$var = $value;
}
// now work with the data from your row
echo "
";
}
[/sourcecode]
Your variables are created with the name of the table attribute, thus $row['address'] becomes $address.
The benefits of this second approach would far outweigh the processing cost of converting the row to simple variables unless you're working with a very high volume site where processor cycles are a significant issue. In that case, this simplified method would serve you well during the development phase, switching to row elements just before final testing.