You’ve already seen the
each functions, but PHP comes
with numerous other functions for handling arrays. The full list is at
some of these functions are so fundamental that it’s worth taking the
time to look at them here.
Arrays and variables share the same namespace. This means that
you cannot have a string variable called
$fred and an array also called
$fred. If you’re in doubt and your code
needs to check whether a variable is an array, you can use the
is_array function like
echo (is_array($fred)) ? "Is an array" : "Is not an array";
Note that if
$fred has not
yet been assigned a value, an “Undefined variable” message will be
foreach...as loop structure are
excellent ways to walk through an array’s contents, sometimes you need
to know exactly how many elements there are in your array,
particularly if you will be referencing them directly. To count all
the elements in the top level of an array, use a command such as the
Should you wish to know how many elements there are altogether in a multidimensional array, you can use a statement such as:
echo count($fred, 1);
The second parameter is optional and sets the mode to use. It should be either a 0 to limit counting to only the top level, or 1 to force recursive counting of all subarray elements, too.
Sorting is so common that PHP provides a built-in function. ...