Specifying an Array Not Beginning at Element 0

Specifying an Array Not Beginning at Element 0


You want to assign multiple elements to an array in one step, but you don't want the first index to be 0.


Instruct array( ) to use a different index using the => syntax:

$presidents = array(1 => 'Washington', 'Adams', 'Jefferson', 'Madison');


Arrays in PHP'like most, but not all, computer languages'begin with the first entry located at index 0. Sometimes, however, the data you're storing makes more sense if the list begins at 1. (And we're not just talking to recovering Pascal programmers here.)

In the Solution, George Washington is the first president, not the zeroth, so if you wish to print a list of the presidents, it's simpler to do this:

foreach ($presidents as $number => $president) {
    print "$number: $president\n";

than this:

foreach ($presidents as $number => $president) {
    print "$number: $president\n";

The feature isn't restricted to the number 1; any integer works:

$reconstruction_presidents = array(16 => 'Lincoln', 'Johnson', 'Grant');

Also, you can use => multiple times in one call:

$whig_presidents = array(9 => 'Harrison', 'Tyler',[] 12 => 'Taylor', 'Fillmore');

PHP even allows you to use negative numbers in the array( ) call. (In fact, this method works for non-integer keys, too.) What you'll get is technically an associative array, although as we said, the line between numeric arrays and associative arrays is often blurred in PHP; this is just another one of these cases:

$us_leaders = array(-1 => 'George II', 'George III', 'Washington');

If Washington is the first U.S. leader, George III is the zeroth, and his grandfather George II is the negative-first.

Of course, you can mix and match numeric and string keys in one array( ) definition, but it's confusing and very rarely needed:

$presidents = array(1 => 'Washington', 'Adams', 'Honest' => 'Lincoln', 'Jefferson');

This is equivalent to:

$presidents[1]         = 'Washington';   // Key is 1
$presidents[]          = 'Adams';        // Key is 1 + 1 => 2
$presidents['Honest']  = 'Lincoln';      // Key is 'Honest'
$presidents[]          = 'Jefferson';    // Key is 2 + 1 => 3

See Also

Documentation on array( ) at http://www.php.net/array.

 Python   SQL   Java   php   Perl 
 game development   web development   internet   *nix   graphics   hardware 
 telecommunications   C++ 
 Flash   Active Directory   Windows