Try this;
>>> $string = 'ABCCDF[GH]IJJ[KLM]';
=> "ABCCDF[GH]IJJ[KLM]"
>>> preg_match_all('/\[(\w+)\]/', $string, $matches);
=> 2
$matches
will look like below.
[
[
"[GH]",
"[KLM]",
],
[
"GH",
"KLM",
],
]
2
solved How to I can split match letter in string PHP