programming-for-dummies

506
Using Arrays
Using Arrays
PHP creates arrays that can hold any type of data and grow as large as you
need them without having to define a size ahead of time. To create an array,
define an array name, the data you want to store, and the index number
where you want to store that item in the array like this:
$arrayname[index] = data;
So if you wanted to store the string “Hello” and the number 4.23 in the
first and second elements of an array, you could do the following:
$myarray[0] = “Hello”;
$myarray[1] = 4.23;
For greater flexibility in retrieving data, PHP lets you create associative
arrays, which let you identify data by a unique string (called a key) rather
than an arbitrary index number. Instead of assigning data to a specific index
number, you assign data to a unique string, such as
$arrayname[“key”] = data;
If you wanted to assign the number 3.14 to the “pi” key, you’d do this:
$myarray[“pi”] = 3.14;
To retrieve data from an associative array, use the key value, such as
$variable = $arrayname[“key”];
So if you wanted to retrieve data stored under the key “pi”, you could do
the following:
$myarray[“pi”] = 3.14;
$number2use = $myarray[“pi”];
The first line stores the value 3.14 into the array and assigns it to the key
“pi”. The second line yanks out the data, associated with the key “pi”, and
stores that data into the $number2use variable.
PHP includes a library of built-in array functions for manipulating arrays
such as array_pop (which removes the last element from an array),
array_push (which adds an element to the end of an array, and sort
(which sorts arrays in ascending order).