An array is a list of values. If we write $num=5; then $num is not an array. If, however, we write $num[0]=5; then we have created an array. Usually, when we create an array we initialize it to several values. We could do this by writing $toppings=array('sausage','pepperoni','mushrooms','extra cheese'); We have now created an array called $toppings. The array is zero indexed meaning the if we write echo $toppings[0]; it will print out sausage.
There are several built-in functions for dealing with arrays. If we write sort($toppings); then print out $toppings[0] it will print extra cheese. Instead of using a constant for the index (also called subscript) we can use a for loop to print out the entire array;
<?php
$toppings=array('sausage','pepperoni','mushrooms','extra cheese');
sort($toppings);
for($i=0;$i<sizeof($toppings);$i++) {
echo $toppings[$i].' ';
}
echo '<br />'; //end the line
?>
We can also print out all of the toppings using a foreach loop:
foreach($toppings as $key=>$info) {
echo $info.' ';
}
echo '<br />'; //end the line
The elements of an array do not have to have a numeric index. Consider the following:
$state['MD']='Maryland';
$state['VA']='Virginia';
$state['NY']='New York';
foreach($state as $key=>$info) {
echo "$key $info<br />"; //prints MD Maryland, etc.
}
In this case a for loop would not work and we would need to use the foreach loop. Also, we must sort this array using asort() NOT sort()