A
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I use ^[0-9a-d]*$ to restrict the user input character must within '0'-'9'
or 'a'-'d', but how can I restric that the input character must not
duplicate
a91b
d23c
is ok
but
c9aa
112
...
is not ok
How can I do it?
or 'a'-'d', but how can I restric that the input character must not
duplicate
a91b
d23c
is ok
but
c9aa
112
...
is not ok
How can I do it?