PHP: Array's

Introduction
This is my first article in English. I have chosen for an article about array's in PHP because it makes the life of a php scripter easier.

Arrays are very useful in combination with mysql queries. Before starting with this tutorial please learn the basic about PHP like echo, variables and strings.

What is an Array?
An Array is a Variable with more than one string.

A variable have one string, see the example code:

$usernameta = 'edward'; $usernameb = 'john'; $agea = '20'; $ageb = '34'; echo $usernamea.'age is '.$agea.'<br />'; echo $usernameb.'age is '.$ageb.'<br />';

The same result with two arrays, one for the age and one for the username:

$username[0] = 'edward'; $username[1] = 'john'; $age[0] = '20'; $age[1] = '34'; echo $username[0].'age is '.$age[0].'<br />'; echo $username[1].'age is '.$age[1].'<br />';

The first number for a array is 0, unaltered as all other numbering in php.


The power of arrays
In combination with other functions from php you can make an automatic loop, this is not possible with normal variables. I show an example

with for

<?php // how many users? $show = 3; $username[0] = 'edward'; $username[1] = 'john'; $username[2] = 'eddy'; $username[3] = 'Richard'; //I have leave the numbers, php know that automatic. $age[] = '20'; $age[] = '34'; $age[] = '13'; $age[] = '19'; echo 'The first three users:<br />'; for ($count = 0; $count < $show; $count++) { echo $username[$count].' age is '.$age[$count].'<br />'; } ?>

The output is:

The first three users: edward age is 20 john age is 34 eddy age is 13

An another method for filling an array with the same result is:

$username = array('edward','john','eddy','richard');

Not only a rising numbering is possible, you can use also give a name. For example:

$connect['server'] = 'localhost'; $connect['database'] = 'databasename'; $connect['user'] = 'root'; $connect['password'] = 'dontshowme';

in_array
There are a lot of functions for using with arrays, I show one function: in_array. With in_array you check of something present is in the array.

<?php $username[0] = 'edward'; $username[1] = 'john'; $username[2] = 'eddy'; $username[3] = 'Richard'; $me = 'Richard'; if (in_array($me,$username)){ echo'Richard is present!'; } ?>

Mistakes in this article about my English please sent a private message . Please feel free to add your questions and comments.

for ($count = 0; $count <= $show-1; $count++) is the same as:
for ($count = 0; $count < $show; $count++).
This version is faster (not much but it is faster) because it doesnt has to calculate the $show - 1 at every loop. Besides that, I think it looks nicer.

$connect[server] = 'localhost'; $connect[database] = 'databasename'; $connect[user] = 'root'; $connect[password] = 'dontshowme';

server,database,user,password aren't constants. They are strings, so they should be used within '' or "":

$connect['server'] = 'localhost'; $connect['database'] = 'databasename'; $connect['user'] = 'root'; $connect['password'] = 'dontshowme';

All the PHP array functions: (Log in om link te zien!)

I don't like the way you use two different arrays for information about the users. Besides that, age should be an integer, so there's no need for ''.

<?php $user[0]->name = 'edward'; $user[0]->age = 20; $user[1]->name = 'john'; $user[1]->age = 34; $user[2]->name = 'eddy'; $user[2]->age = 13; $user[3]->name = 'Richard'; $user[3]->age = 19; ?>

<?php $user['name'][0] = 'edward'; $user['age'][0] = 20; $user['name'][1] = 'john'; $user['age'][1] = 34; $user['name'][2] = 'eddy'; $user['age'][2] = 13; $user['name'][3] = 'Richard'; $user['age'][3] = 19; ?>

That's not very logical.

The age and name are assigned to the user. That isn't the case in your code.

<?php $user[0]->name = 'edward'; $user[0]->age = 20; $user[1]->name = 'john'; $user[1]->age = 34; $user[2]->name = 'eddy'; $user[2]->age = 13; $user[3]->name = 'Richard'; $user[3]->age = 19; foreach($user AS $key => $value){ echo $key.": ".$value->name." - ".$value->age."<br>"; } ?>

Or imagin this

<? $user[0]->name="henk"; $user[0]->age=13; $user[1]->name="jaap"; $user[1]->age=25; $user[2]->name="jan"; $user[2]->age=15; $user[0]->friends[0]=$user[1]; $user[0]->friends[1]=$user[2]; print_r($user); ?>

returns:

Array ( ....[0] => stdClass Object ........( ............[name] => henk ............[age] => 13 ............[friends] => Array ................( ....................[0] => stdClass Object ........................( ............................[name] => jaap ............................[age] => 25 ........................) ....................[1] => stdClass Object ........................( ............................[name] => jan ............................[age] => 15 ........................) ................) ........) ....[1] => stdClass Object ........( ............[name] => jaap ............[age] => 25 ........) ....[2] => stdClass Object ........( ............[name] => jan ............[age] => 15 ........) )

Replaced the spaces with .'s

Patrick,

You are using a object in a array, and it isn't necessary

$person[]= array('Name' => 'Jaap', 'Age' => 20);

Thats the best way

Thanks for the comments.

Moderators: Please edit this article with the comments from Mark de Voogd (first comment) for a correct article.

Tell how how that's better than using objects.

It's all about the structure.
With objects, you'll get an array of users.

Not to say your way doesn't work. It'll just get pretty ugly if your data is more complex. Besides that, I don't like to use integers/strings etc all in one array. Objects are made for that purpose.

// how many users? $show = 3;

Why don't you use sizeof?
(Log in om link te zien!)

The array have 4 users and i want to show 3 users. Sizeof is very useful to show the whole array.