PHP preg_replace跳过匹配重叠的地方

Question

I've been Googling this regex behavior all afternoon.

$str = ' b c d w i e f g h this string';

echo preg_replace('/\s[bcdefghjklmnopqrstuvwxyzBCDEFGHJKLMNOPQRSTUVWXYZ]{1}\s/', ' ', $str);

I want to remove all instances of a single character by itself (except for A and I) and leave one space in its place. This code appears to work on every other match. I suspect this is because the matches overlap each other.

I suspect a lookaround would be appropriate here, but I've never used them before and could use a snippet.

EDIT: Just to avoid confusion about what I am trying to accomplish. I want to turn the above string into this:

$str = ' i this string';

Notice all single-letter characters that are NOT "A" or "I" have been removed.

Answer 1

You can try this:

/(?<=\s)[b-hj-zB-HJ-Z](?=\s)/

or modify the ranges if you dont need both i and I.