PHP regex - valid float number

Question

I want user only input 0-9 and only once \".\"

 patt = /[^0-9(.{1})]/

 1.2222 -> true
 1.2.2  -> false (only once \'.\')

help me , t

Answer 1

this is what you're looking for

$re = "~        #delimiter
    ^           # start of input
    -?          # minus, optional
    [0-9]+      # at least one digit
    (           # begin group
        \.      # a dot
        [0-9]+  # at least one digit
    )           # end of group
    ?           # group is optional
    $           # end of input
~xD";

this only accepts "123" or "123.456", not ".123" or "14e+15". If you need these forms as well, try is_numeric