PHP: Best way to split string into alphabetic and numeric components

Question

I have several strings of the format

AA11
AAAAAA1111111
AA1111111

Which is the best (most efficient) way to sepa

Answer 1

preg_split should do the job fine.

preg_split('/(\w+)/', $input, -1, PREG_SPLIT_DELIM_CAPTURE);

The preg library is surprisingly efficient in handling strings, so I would assume it to be more efficient than anything you can write by hand, using more primitive string functions. But do a test and see for your self.