PHP MYSQL LESSON 6 ( PART 2 ) _ ARRAY IN PHP

Strings containing valid decimal integers, unless the number is preceded by a + sign, 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.
If multiple elements in the array declaration use the same key, only the last one will be used as all others are overwritten.

Example #2 Type Casting and Overwriting example

"a",
"1" => "b",
1.5 => "c",
true => "d",
);
var_dump($array);
?>
The above example will output:

array(1) {
[1]=>
string(1) "d"
}
As all the keys in the above example are cast to 1, the value will be overwritten on every new element and the last assigned value "d" is the only one left over.

PHP arrays can contain integer and string keys at the same time as PHP does not distinguish between indexed and associative arrays.

Example #3 Mixed integer and string keys

"bar",
"bar" => "foo",
100 => -100,
-100 => 100,
);
var_dump($array);
?>
The above example will output:

array(4) {
["foo"]=>
string(3) "bar"
["bar"]=>
string(3) "foo"
[100]=>
int(-100)
[-100]=>
int(100)
}
The key is optional. If it is not specified, PHP will use the increment of the largest previously used integer key.