how does this example work?

ShawnD

my book has a strange example on page 27 (very beginning) and it doesn't explain how it works exactly

$person[0] = "Edison";
$person[1] = "Wankel";
$person[2] = "Crapper";

$creator['Light bulb'] = "Edison";
$creator['Rotary Engine'] = "Wankel";
$creator['Toilet'] = "Crapper";

$person = array('Edison', 'Wankel', 'Crapper');
$creator = array('Light bulb'        => 'Edison',
                        'Rotary Engine' => 'Wankel',
                        'Toilet'             => 'Crapper');

foreach ($person as $name) {
echo "Hello, $name\n";
}
foreach ($creator as $invention => $inventor) {
echo "$inventor created the $invention\n";
}

the output should be:
Hello, Edison
Hello, Wankel
Hello, Crapper
Edison created the Light bulb
Wankel created the Rotary Engine
Crapper created the Toilet

ok now how does that work exactly?
the $person[] thing was an array of people and i understand that. $creator[] is an array with the invention as the name of that one in the array and the assigned value to that part of the array is the creator and i understand that. assigning $person to being an array with the value of 3 people makes sense to me as well.
the $creator part, i do not understand. what do those => things mean?
on that first foreach line, does the part of ($person as $name) mean that it just created an array called $name which is exactly the same as the $person array?

if i knew what that => thing meant, i would probably be able to figure out the rest but i don't.

dannys

$creator = array('Light bulb'        => 'Edison',
                        'Rotary Engine' => 'Wankel',
                        'Toilet'             => 'Crapper');

This code creates an associative array (also called a hash in many other languages)

The array elements are referenced using strings instead of indices.

echo $creator['Light bulb'];

would print Edison in the example above

The foreach loop basically means 'iterate through array $person, placing the element in $name' - It's a really easy way of processing an entire array.

The 2nd foreach loop is pretty similar but it also places the array's key in $invention

http://www.php.net/manual/en/language.types.array.php
http://www.php.net/manual/en/control-structures.foreach.php

suspy

$creator['Light bulb'] = "Edison";
$creator['Rotary Engine'] = "Wankel";
$creator['Toilet'] = "Crapper";
and
$creator = array('Light bulb' => 'Edison',
'Rotary Engine' => 'Wankel',
'Toilet' => 'Crapper');
do the same thing;

foreach(array_expression as $key => $value) statement

like 'Light bulb' is $key and like 'Edison' is $value;
statement will be executed sizeof(arrary_expression) times;

jmcneese

think of 'as' as an alias/reference. in other words, for each item in the array $person, reference the current item as $name.

in the second example, it uses referencing aliases as well, in that you say for each item in the $creator array (which stores information in an [key] => [value] structure), reference the key as $invention and the value as $inventor. maybe you will get a better idea of what the structure looks like if you try this:

$creator = array('Light bulb' => 'Edison',
                           'Rotary Engine' => 'Wankel',
                           'Toilet' => 'Crapper');

echo "<pre>";
print_r($creator);
echo "</pre>";

ShawnD

ok i think i get it, thanks for all your help 🙂