Pixel2Life Forum > Alternating row colours

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Matthew.

May 14 2006, 03:29 PM

Another tutorial written by me a while back, enjoy

In this tutorial i will be showing you how to achieve alternating row colours using PHP.
Something like this will be our outcome:

What we will use

In the tutorial i shall use these functions (linked for reference):

Comparason operators

While() (loops)

define()

And of course of the standard mysql functions for example's sake.

Standard code:

This code is not part of the tutorial, but merely for connecting to the database, Jst copy it if you wish.

CODE

The learning bit....

Yup,time to learn (awwww!)

First off im going to use define(); to set the 2 BG colours we want. These are the colours that will alternate.

define is very simple:

define( mixed value, case sensitive value )

Note that since were using HEX we dont need to worry about case's, btu normall you should take note of it.

OK.

CODE

define("Bg1", "#FFF");
define("Bg2", "#EEE");

So we set one variable "Bg1" and one "Bg2" kinda self explanatory huh? The first is #FFF (white) and the 2nd #EEE (grey---ish).

The next 2 lines are again, basic stuff.

CODE

$i = 0;
$Query = @mysql_query("SELECT title FROM `example` ORDER BY id DESC") or die('Error: '.mysql_error());

We are setting $i as 0 as we are going to sue it in a loop to alternate the colour values, the 2nd line in the mysql query that you change to suit your needs.

(notice that we are supressing error's using @ and creating our own at the end.)

Now for the real code, This part changes the colours are echo's out the data.

CODE

while( $row = mysql_fetch_array($Query) )
{
        $i = ($i > 1 ? '0' : $i );
        $loopedBG = ($i > 0 ? Bg1 : Bg2 );
        echo "<div style='background-color: $loopedBG;'>{$row['title']}</div>";

                $i++;
}

First we begin a while() loop, this takes all the data from the query and displays it.

CODE

$i = ($i > 1 ? '0' : $i );

This is a ternary operator, as explan in 2 past tutorials, basically,it works like this:

string name = (condition ? value if true: value if false);

So this one, it checking if $i is greater than 1, if it is, reset i to 0, if not carry on with its current value

CODE

$loopedBG = ($i > 0 ? Bg1 : Bg2 );

This line is what changes the colour, is laymens terns its:

IF $i is greater than Zero, value is Bg1 if not value if Bg2

And remember we set Bg1 and Bg2 earlier.

CODE

echo "<div style='background-color: $loopedBG;'>{$row['title']}</div>";

This is again, self explanatory, we are simply echo'ing the data within a DIV. The DIV has a srtyle property and notice that the colour is not set by you, but by the varable $loopedBG

Notice there are curly braces around $row['title'], this is because we are access'ing an array within double quotes and is standard practice.

Now,

I know what your thinking, "We did all this checking if $i has changed, but it doesnt, because we havent done anything to change it....?".

Well, you'd be correct, we havent, but now we have!....

CODE

$i++;

This ADDS 1 to the current value of $i every time the loop goes round.

Its the same as using

CODE

$i = $i +1;
or
$i = $i++;

But the above would be pointless

Now we simply close the loop and end the script!!

Done!!

Heres the complete code:

CODE

<?php
$config = array(
             'user' => 'username',
             'pass' => 'password',
             'DB' => 'database_name',
             'host' => 'localhost'
            );
    @mysql_connect($config['host'], $config['user'], $config['pass']) or die(mysql_error());
    @mysql_select_db($config['DB']) or die(mysql_error());

    define("Bg1", "#FFF");
    define("Bg2", "#EEE");

    $i = 0;
    $Query = @mysql_query("SELECT title FROM `example` ORDER BY id DESC") or die('Error: '.mysql_error());
        while( $row = mysql_fetch_array($Query) )
        {

                 $i = ($i > 1 ? '0' : $i );
                $loopedBG = ($i > 0 ? Bg1 : Bg2 );

                 echo "<div style='background-color: $loopedBG;'>{$row['title']}</div>";
                 $i++;
        }
?>

Enjoy

Indigo

May 15 2006, 06:24 AM

Thanks a lot for sharing:)
You could probably just use $i = 1; too.

Can you please explain why you´re using define instead of just $bg1 = #fff; and then use ($i > 0 ? $bg1 : $bg2 ); ?

Matthew.

May 15 2006, 11:48 AM

Its just my way, define is usually not used this way i will admit, its more suited to database connections details and similar where you dont wish the vriable to be changed by someone who's just read a nice little tutorial on script owning.

Its a habit lol. It really doesnt matter though

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