Useful PHP Functions

Today I thought I would share with you some useful PHP functions which help speed up my programming life.  Some of these functions I have built myself, some have been collecting from the Internet during my searches. Please feel free to add any more you many have in the comments section:

1. Randomized String

This function is great for generating randomized passwords and ‘guids’ which I use for identifying logged in users.

function guid($length=50) {
   $characters = '0123456789abcdefghijklmnopqrstuvwxyz';
   $string = '';    

   for ($p = 0; $p < $length; $p++) {
       $string .= $characters[mt_rand(0, strlen($characters))];

   return $string;

2. MySQL Date

This function quickly converts dd/mm/yyyy to yyyy-mm-dd (which is how MySQL likes it input):

function mysqlDate($thedate) {
$date_array = explode('/',$thedate);
return $date_array[2].'-'.$date_array[1].'-'.$date_array[0];

3. Display MySQL Date

Reverses the previous function, takes a MySQL date (yyyy-mm-dd) and returns as dd/mm/yyyy:

function displayMysqlDate($thedate) {
$date_array = explode('-',$thedate);
return $date_array[2].'/'.$date_array[1].'/'.$date_array[0];

4. Convert Date and Time to mktime()

These functions take a MySQL Date (and time if present) and convert it into a mktime() format which can then be used in the PHP Date() function to display however you want:

function showTime($time) {
if ($time=='') return 0;
else return $time;

function mkTimeMysqlDate($timedate) {
$full_array = explode(' ',$timedate);
$date_array = explode('-',$full_array[0]);
$time_array = explode(':',$full_array[1]);

return mktime(showTime($time_array[0]),showTime($time_array[1]),showTime($time_array[2]),$date_array[1],$date_array[2],$date_array[0]);

5. Filename friendly string

This function returns the enter string ‘filename-friendly’, whereby removing all none letters and numbers and replacing with a hyphen “-”.

I usually call this function using the following command (which could simply be incorporated into the function below): $url = checkCharacters(strtolower(trim(stripslashes($title))));

function checkCharacters($title) {
$final_text = '';

for ($i=0;$i $letter = substr($title,$i,1);
$ascii = ord($letter);
if (($ascii>=97 && $ascii=48 && $ascii 
else $final_text .= "-";

return $final_text;

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