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The normal way of looping through a directory is to get a handle on the directory, then go through each item, making sure that the file is readable and is not "." or ".." before doing something with the file. Because this is done a lot the DirectoryIterator() object was created in PHP5 to simplify this process.

The constructor of the DirectoryIterator() object takes a single parameter, this is the path of the directory that is to be iterated over.

$dir = new DirectoryIterator('/');

To get the current working directory you can use the PHP function getcwd(). This will return the directory that the PHP script is being run from.

$dir = new DirectoryIterator(getcwd());

The previous bit of code will open up the root directory of your server. If you are on a Linux server you will see directories like dev, var, srv, etc, lib, home, root, sbin and usr.

Use the following function to pad a string with to a set length with a given string. The function takes three parameters. The string to be padded, the total number of characters that the string must be, and the string to be added. If the third parameter is not given then 0 is used as a default.

function pad(padMe, totalChars, padWith) {
  padMe = padMe + ""; // force num to be string
 padWith = (padWith) ? padWith :"0"; // set default pad
 if ( padMe.length < totalChars ) {
  while ( padMe.length < totalChars ) {
    padMe = padWith + padMe;
  }
 }
 return padMe;
}

Here are some examples of the function in action. If the string given is longer than the required pad length then the string is returned unchanged.

Counting the number of words in a block of text can be tricky. Users tend to create sections of white space that can throw out most scripts that don't take this into consideration.

I have created a tool for #! code that looks at a textarea of a form, and prints the number of words into an input box in the same form. The textarea calls a function called textCounter() every time a key is pressed. Here is the HTML of the form.

<form onsubmit="return false;" action="" id="wordCountCalc">
<textarea name="message1" rows="10" cols="68" onkeydown="textCounter()" onkeyup="textCounter()"></textarea>
<input readonly="readonly" size="15" type="text" name="len" maxlength="10" value="0" />
</form>

The function works by removing any white space from the start of the text. It then removes any tab characters from the text before splitting the text by one or more white space characters.

To limit the number of rows returned in a MS SQL query you need to use the TOP command. This goes before you name the columns that are to be returned by the SELECT statement.

The following query returns the first 35 rows from a table.

Encoding special characters in a block of HTML or other code can be a pain because there might already be ampersands there that impart encoding. This might be an ampersand that has already been encoded with a &, or it might be an ampersand in the code as an if statement or similar.

Use the following regular expression to find any ampersand that hasn't already been encoded.

([^&])&(?!#?[a-zA-Z0-9]{2,6};|\$|&)

When using replace, you can turn any ampersand into & by using the following replace.

$1&

The only problem with this statement is when the code uses a & operator as part of a statement to do bitwise operations.

If you have a table of incremental values it can be hard to find out which ones are missing. The only solution might be to write a script to get all the data from the database and see which ones are missing. However, there is a way of doing this without using a script.

Using a standard select query like this:

SELECT * FROM table;

Gets the following data:

1
3
10
23

We can see that values are missing, but which ones? The following query will show us where the gaps are in the data of the table.

SELECT t1.id+1 as Missing
FROM table as t1
LEFT JOIN table  as t2 ON t1.id+1 = t2.id
WHERE t2.id IS NULL
ORDER BY t1.id;

Produces the following result.

If you find that you are having trouble sorting data in a VARCHAR column in a MySQL database then you can try the following trick.

Lets say that you had the values 1,200,30,4000 and 5 and that you inserted them into the database in that order. When the following query is run on this data:

SELECT numbers FROM table ORDER BY numbers;

The following output is seen.

1
200
30
4000
5

This is clearly not the correct order, although it represents the order of. You can force a natural order to the sort by using a "+0" after the colum you are trying to sort by.

SELECT numbers FROM table ORDER BY numbers+0;

This produces the following output, which is sorted as you expect a set of numbers to be sorted.

I found a little problem today when processing a bit of text from a non-english site. I found that the text was being loaded properly, but because it was in UTF-8 encoding PHP couldn't use htmlspecialchars() or apply get_html_translation_table() to the string to properly encode the foreign characters. These methods just don't have any effect. This is because PHP (before version 5.2.x) doesn't natively support unicode character encoding and is therefore not able to translate characters in UTF-8 format.

To get around this just use the utf8_decode() function on the string to convert it into a usable format.

DOS Batch is the Windows equivalent of shell scripting and can be used to perform all sorts of different actions. Anything that you type into a DOS prompt on a Windows machine can be used in a bat file to quickly do something that you would otherwise have to repeat many times over. To create a bat file just make a file and give it the extension "bat". If you run a DOS prompt and navigate to the directory that the bat file exists in you can type the name of the file to get it to do certain actions. If you called your file "action.bat" you can run it by typing "action" or "action.bat". Starting with a simple example, if you want to print the contents of a file to screen then you need the type command, followed by the file.

type file.txt

However, this puts a lot of rubbish on the screen. If you wanted to create a backup of that file then you would write the following.

I found this very handy function on the php.net site in the user comments for the strlen() function. It accepts a string in ASCII or UTF-8 format and finds out how long that string is in bytes.

The function works by going through the string and adding how many bytes each character represents. For normal ASCII values this is a single byte so 1 is added to the total. Unicode characters can be up to 6 bytes and so the rest of this function works out how many bytes the character takes up by using AND calculations.