How to replace exact matches on word boundary in PHP?

Question

PHP

There is a line: Roads are not cleaned not only in the North-Eastern Administrative District, but also in the South-Eastern Administrative District, as well as in the Eastern Administrative District, CJSC ...
There is an array:
Northern Administrative District * North, North-Eastern Administrative District
* North-Eastern
Administrative District * Eastern Southern -Eastern Administrative District
* South-Eastern

Administrative District * Western understand how to go through each first element of the array (separator - *) along the line and replace exact matches with the second element of the array.
I tried preg_replace, but something doesn't work - all matches are replaced, even if it's part of a word, but it should be exactly.
Please tell me how to solve.

Answer 1

$arr = [
  'САО' => 'северный',
  'СВАО' => 'северо-восточный',
  'ВАО'  => 'восточнй',
  'ЮВАО' => 'юго-восточный',
  'ЗАО' => 'западный',
];

$text = str_replace(array_keys($arr), array_values($arr), $text);

If the replacement is by exact occurrence, then you still should not use regular expressions, it is better to use string functions.