4.8. Appending One Array to Another
Use array_merge( ):
$garden = array_merge($fruits, $vegetables);
$p_languages = array('Perl', 'PHP'); $p_languages = array_merge($p_languages, array('Python')); print_r($p_languages); Array (  => PHP  => Perl  => Python )
Accordingly, merged arrays can be either preexisting arrays, as with $p_languages, or anonymous arrays, as with array('Python').
array_push($p_languages, array('Python')); print_r($p_languages); Array (  => PHP  => Perl  => Array (  => Python ) )
Merging arrays with only numerical keys causes the arrays to get renumbered, so values aren't lost. Merging arrays with string keys causes the second array to overwrite the value of any duplicated keys. Arrays with both types of keys exhibit both types of behavior. For example:
$lc = array('a', 'b' => 'b'); // lower-case letters as values $uc = array('A', 'b' => 'B'); // upper-case letters as values $ac = array_merge($lc, $uc); // all-cases? print_r($ac); Array (  => a [b] => B  => A )
The uppercase A has been renumbered from index 0 to index 1, to avoid a collision, and merged onto the end. The uppercase B has overwritten the lowercase b and replaced it in the original place within the array.
print_r($a + $b); print_r($b + $a); Array (  => a [b] => b ) Array (  => A [b] => B )
Since a and A both have a key of 0, and b and B both have a key of b, you end up with a total of only two elements in the merged arrays.
In the first case, $a + $b becomes just $b, and in the other, $b + $a becomes $a.
However, if you had two distinctly keyed arrays, this wouldn't be a problem, and the new array would be the union of the two arrays.
4.8.4. See Also
Documentation on array_merge( ) at http://www.php.net/array-merge.
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