PHP extracts characters in a string as part of

PHP extracts the character parts of a string
$str 1 = ' abc12 ';
$str 2 = ' edf3 ';

How to extract variables $str1 and $str2 in just the character part (extracting ' abc ' from $STR1, extracting ' EDF ' from $STR2)?

------Solution--------------------

PHP Code

[[email protected] php_project]$ PHP main.php abcdefg[[email protected] php_project]$ cat main.php 
  
  
------Solution--------------------
Take out all the letters
echo preg_replace ('/[^a-z]/i ', ', $str 1);

Just take the letter from the front.
echo preg_replace ('/^ ([a-z]+). */i ', ' $ $ ', $str 1);
