regex - 先行ゼロを禁止する正の数値 (5,2) を要求する正規表現

Question

正規表現パターンは、数値に対して次の制約の組み合わせを強制できますか?

     the number must be >= 1 and <= 999 
     (decimal point cannot be the first character in the string?)

     the number can be an integer or a number with a fractional component

     when it has a fractional component, 
     no more than 2 digits to the right of the decimal point 
     EDIT: but at least one digit to the right

     must not have leading zero(s)

Answer 1

はい..

^(?!999[.](0*[1-9]+$))(?!0|[.])\d{1,3}([.]\d{1,2})?$

Answer 2

私はこれで行きます：

/^
(?:
  999.0*                      # 999.000
  |                           # or
  [1-9]\d{,2}((?<!999)\.\d+)? # 1-998 plus optional .\d*
)
$/x