Does PHP Treat Numeric Strings as Array Keys Differently Than Integers?

Numeric Strings as Array Keys in PHP

PHP allows the use of numeric values as array keys. However, when using numeric strings (e.g., "123"), PHP automatically converts them to integers. This behavior can be problematic if you want to preserve the key's string value.

Consider the following code:

$blah = ['123' => 1];
var_dump($blah);

Output:

array(1) {
  [123] =>
  int(1)
}

As you can see, the key "123" was converted to an integer. To prevent this, PHP does not support using numeric strings as array keys without conversion.

According to the PHP manual:

"A key may be either an integer or a string. If a key is the standard representation of an integer, it will be interpreted as such (i.e. "8" will be interpreted as 8, while "08" will be interpreted as "08")."

In contrast to JavaScript, where numeric strings and integers can be used interchangeably as object keys, PHP treats numeric strings as integers when used as array keys. This can lead to unexpected results, particularly when working with JSON data.

To avoid potential issues, it's recommended to use only strings or integers as array keys in PHP. If you need to work with both types of keys, consider using an object instead of an array.

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