Creating Arrays
PHP provides the array( ) language construct that creates arrays. The following examples show how arrays of integers and strings can be constructed and assigned to variables for later use:
$numbers = array(5, 4, 3, 2, 1);
$words = array("Web", "Database", "Applications");
// Print the third element from the array
// of integers: 3
echo $numbers[2];
// Print the first element from the array
// of strings: "Web"
echo $words[0];
By default, the index for the first element in an array is 0. The values contained in an array can be retrieved and modified using the bracket [ ] syntax. The following code fragment illustrates the bracket syntax with an array of strings:
$newArray[0] = "Potatoes"; $newArray[1] = "Carrots"; $newArray[2] = "Spinach"; // Oops, replace the third element $newArray[2] = "Tomatoes";
Numerically indexed arrays can be created to start at any index value. Often it's convenient to start an array at index 1, as shown in the following example:
$numbers = array(1=>"one", "two", "three", "four");
Arrays can also be sparsely populated, such as:
$oddNumbers = array(1=>"one", 3=>"three", 5=>"five");
An empty array can be created by assigning a variable with no parameters with array( ). Values can then be added using the bracket syntax. PHP automatically assigns the next numeric index-the largest current index plus one-when an index isn't supplied. Consider the following example, which creates an empty array $errors and tests whether that array is empty at the end of the script. The first error added with $errors[] is element 0, the second is element 1, and so on:
$errors = array( ); // later in the code .. $errors[] = "Found an error"; // ... and later still $errors[] = "Something went horribly wrong"; // Now test for errors if (empty($errors)) // Phew. We can continue echo "Phew. We can continue"; else echo "There were errors";