When I’m developing the online form creator that enables the users to create form fields that accept only certain type of numbers, I need to verify if a given string is a valid natural number such as 1, 2, 3, 4, …. I’m writing the code / functions in PHP but you can literally use …
The strange thing is that the native empty() function of PHP treats a string of ‘0’ as empty: $str = ‘0’; echo empty($str) ? ’empty’ : ‘non-empty’; And it will output ’empty’. Therefore if you need to examine if a string is truly an empty string with zero length, you have to use: echo strlen($str) …
PHP: True empty() function to check if a string is empty or zero in length Read More »
I created a free online web form builder a while back and since it went well in search engine rankings, spammers and phishers found it and started to use it creating forms to collect email account usernames and passwords through phishing attempts. I’ve got to do something before my host closes down my site because …
PHP: Checking Text Strings against Reserved or Censored Words Read More »
The easy way to add a username and password pair in the .htpasswd file is to use an online password generator tool that converts the clear text password into its hash, a.k.a. the encrypted password. The problem with this approach is that you have to manually create the pair and append it to .htpasswd. Is …
How to create / generate .htpasswd password with PHP dynamically? Read More »
Depending on the web server software you use, your PHP script will be consuming significantly different amount of memory (RAM). If you are using Apache without proper optimization, the simplest request that does nothing but returns a status code will need 150kB of memory. Multiply this by 2000 visits per day and by 10 sites …
Check how much memory your PHP script is using. (PHP script memory usage) Read More »
When you read the content of any specified directory with PHP functions such as scandir() or readdir(), they will return both files and directories. How does one get just the child directories of a given directory in PHP? The obvious solution is the is_dir() function that checks if a filename is a directory: $all = …
How to get all the sub-directories of a given directory in PHP? Read More »
If you have mysqli extension installed with PHP and you use it to perform database operations, after you have tried to connect to MySQL by: $conn = new mysqli(‘localhost’, ‘db_user’, ‘db_pwd’, ‘db_name’); You can then check if the connection is successful by: if ($conn -> connect_errno) { // failure } else { // success } …
How to check if a MySQL database connection is successful in PHP? Read More »
When I was creating an installation script, I needed to check if a table exists to make sure the installation had not been performed yet. How did I do that? I use this simple query to get whether a table exists in the specified database: SELECT table_name FROM information_schema.tables WHERE table_schema = ‘db_name’ AND table_name …
This is a pretty odd question to ask in the first place if you have been using JavaScript for a while. JavaScript files are called from HTML web pages who need them to manipulate the HTML elements so that the users have extraordinary interactive experience. You can’t include a JavaScript file inside another JavaScript file …
How to include a JavaScript file inside a JavaScript file? Read More »
Normally, when users click on any label tag with the cursor, the corresponding input field will be focused ready for input or selection. Therefore, you can always achieve the focus effect by this native function of HTML’s. Otherwise, you’d need a small dime of JavaScript to set focus to any form element on the fly …
To get the URL address of the current page with JavaScript, simply return the value of window.location.href: document.write(window.location.href); Which is the same with: document.write(location.href); There’s much more you can do with the JavaScript Location Object such as redirecting to another URL.
If the website is run on a Linux server, everything that can be run from the web (i.e., from the browser address bar) can be run from the Linux console. That is if you have the SSH access which most hosts provide. Connect to your hosting server via SSH by putty and you will have …
How to execute / run PHP scripts in the background? Read More »
Sometimes you need to temporarily halt the code execution of your PHP script for certain seconds and then automatically resume it. For example, some mail delivery servers have the restriction that you have to wait a certain interval such as 12 seconds before sending another email. You can tell your PHP script to stop for …
PHP: Delay Function that Halt Code Execution Temporarily and Then Resume It Read More »
This is a rather common problem for novice web developers. While it may seem at first glance that it’s easy for PHP and JavaScript to communicate with each other, but they actually cannot interact with each other directly. They are very different technologies built for distinct purposes. How to transfer or pass variable values from …
Static files of JavaScript would survive most applications but sometimes the ability to include PHP code inside JavaScript scripts and generate the content of the script files on the fly by PHP is a better option. How does one do that? The simplest solution is to just include PHP code inside the <script></script> section of …
How to execute / run PHP code inside JavaScript files? Read More »
AND and OR are common logic operators across all programming languages and in MySQL, they mean the same thing. A statement (a.k.a, a condition in any WHERE clauses such as id > 100) can be either true or false. A group / combination of statements can be true or false, depending on their own values …
MySQL logic operators: How to use AND, OR together in WHERE clauses in one query? Read More »
The other day I was very upset about some extraordinary down times of my unmanaged VPS box at Linode. As it’s unmanaged, support staff at Linode are not responsible for the failures. I contacted them and they told me it’s OOM (Out Of Memory), pointing me to the right documentation to figure out how to …
Here’s how you can create yourself the simplest PHP hit counter that records the number of times any resource on your website that has been accessed (visited or downloaded). It can be either a web page or a downloadable file package. The hits number will be stored in a plain text file named count.txt. Hit …
It’s not only insecure but it inconveniently commands the use of PHP function stripslashes() every time you pull something from the database or when you get something from the client side. While most of the hosts out there are using factory settings of PHP that turn off magic_quotes_gpc by default, there are a few that …
Turn off and disable magic_quotes_gpc in .htaccess Read More »
Things couldn’t be worse when you were half way editing something and accidentally navigated away from the editing page after a whole hour of typing work. Hitting the back button of your browser neither helped, all you had done was gone anyway. This must be remedied in some way, if you are creating an application …
JavaScript: Confirmation / Warning before Leaving or Navigating Away from a Page Read More »
