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  1. <?php
  2. $string = 'PrintHelloWorld';
  3. $pattern = '/(?<!^)([A-Z])/';
  4. $replacement = '_$1';
  5. echo preg_replace($pattern, $replacement, $string);
  6. ?>
Success #stdin #stdout 0.01s 20520KB
comments (?)
stdin 
Standard input is empty
stdout 
Print_Hello_World
https://ideone.com/HvjfWW
language:
PHP (php 7.3.5)
created:
10 years ago
visibility:
secret

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