The difference and meaning of PHP regular expression parameter /i, /g, /ig, /gi, /m
/i. />/ig (full text lookup, overlooked case) the character in the
i mode will match the case of the case of the case of
m as a multiline
s, and the string is considered as a single line. In the reverse substitution, we make a normal replacement, use it as a PHP code, and replace the search string with the result.
A coercion only from the beginning of the target string to match the $character in the
D pattern only to match the end of the target string, the last
U matching the nearest string
u mode string is considered as