Learning Resources

Array creation

An array can be created using the array() language construct. It takes any number of comma-separated key => value pairs as arguments.

    key  => value,
    key2 => value2,
    key3 => value3,

The comma after the last array element is optional and can be omitted. This is usually done for single-line arrays, i.e. array(1, 2) is preferred over array(1, 2, ). For multi-line arrays on the other hand the trailing comma is commonly used, as it allows easier addition of new elements at the end.

As of PHP 5.4 use the short array syntax, which replaces array() with [].

Example - A simple array :

$array = array(
    "foo" => "bar",
    "bar" => "foo",

// as of PHP 5.4
$array = [
    "foo" => "bar",
    "bar" => "foo",

The key can either be an integer or a string. The value can be of any type.

Additionally the following key casts will occur:

  • Strings containing valid integers will be cast to the integer type. E.g. the key "8" will actually be stored under 8. On the other hand "08" will not be cast, as it isn't a valid decimal integer.
  • Floats are also cast to integers, which means that the fractional part will be truncated. E.g. the key 8.7 will actually be stored under 8.
  • Bools are cast to integers, too, i.e. the key true will actually be stored under 1 and the key false under 0.
  • Null will be cast to the empty string, i.e. the key null will actually be stored under "".
  • Arrays and objects can not be used as keys. Doing so will result in a warning: Illegal offset type.