gistfile1.php

php > $x = array();
php > $x[8.7] = "hi";
php > var_dump($x);
array(1) {
  [8]=>
  string(2) "hi"
}
php > $x["8"] = "hello";
php > var_dump($x);
array(1) {
  [8]=>
  string(5) "hello"
}