Regex dishes [continue]

Regular dishes (continue for help) aaa. bbb. ccc. ddd $ aaa. bbb. ccc. ddd... aaa. bbb. ccc. how to replace ddd with regular expressions with aaa. bbb. ccc. ddd $. b. c. d... aaa. bbb. ccc. I didn't ask a question for ddd twice. ------ solution ------------------ try it first .. PHPcode $ str regular expression dishes [continue for help]
Aaa. bbb. ccc. ddd $ aaa. bbb. ccc. ddd... aaa. bbb. ccc. ddd
How to replace the regular expression
Aaa. bbb. ccc. ddd $ a. B. c. d... aaa. bbb. ccc. ddd

I have not asked any questions.

------ Solution --------------------
First try it ..

PHP code

$ Str = 'AAA. bbb. ccc. ddd $ aaa. bbb. ccc. ddd... aaa. bbb. ccc. ddd '; echo preg_replace_callback ('/\ $ ([a-z] + )((? :. [A-z] +)/I ', 'test', $ str); function test ($ m) {$ arr = explode ('. ', trim ($ m [0],' $ '); $ join = array (); foreach ($ arr as $) {$ join [] = $ a [0];} return '$ '. implode ($ join ,'. ');}/** output: aaa. bbb. ccc. ddd $. b. c. d... aaa. bbb. ccc. ddd */
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PHP code
   
   
$s = 'aaa.bbb.ccc.ddd $aaa.bbb.ccc.ddd... aaa.bbb.ccc.ddd';echo preg_replace_callback('/\$[^\s]+/', 'back', $s);function back($r) {  return preg_replace('/(\w)+/', '$1', $r[0]);}