- print_r: documentation ( source)
- preg_split: documentation ( source)
<?php
$string = '[this is block
this is also same "block"
this is same block
another same block]
new block!
another new block!
[this is new block
this is also a new block]';
print_r(preg_split('/(\[[^]]+])|\R/', $string, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE));