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  1. <?php
  2.  
  3. $s = "1                #first                  (dog)";
  4. echo preg_replace('~1\s*#~', ',$0', $s);
Success #stdin #stdout 0.01s 52488KB
comments (?)
stdin 
Standard input is empty
stdout 
,1                #first                  (dog)
https://ideone.com/Xq8Pei
language:
PHP (php 7.3.5)
created:
9 years ago
visibility:
secret

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