$str = "JavaScript C C++ PHP NodeJS";
preg_match_all('/[a-z]/', $str, $matches, PREG_OFFSET_CAPTURE);
print_r($matches[0]);
/*
run:
Array
(
[0] => Array
(
[0] => a
[1] => 1
)
[1] => Array
(
[0] => v
[1] => 2
)
[2] => Array
(
[0] => a
[1] => 3
)
[3] => Array
(
[0] => c
[1] => 5
)
[4] => Array
(
[0] => r
[1] => 6
)
[5] => Array
(
[0] => i
[1] => 7
)
[6] => Array
(
[0] => p
[1] => 8
)
[7] => Array
(
[0] => t
[1] => 9
)
[8] => Array
(
[0] => o
[1] => 22
)
[9] => Array
(
[0] => d
[1] => 23
)
[10] => Array
(
[0] => e
[1] => 24
)
)
*/