Regular expression for positive decimal number with 0, 1 or 2 decimal places

Question

Please help me make regular expression for positive decimal number with 0, 1 or 2 decimal places. It must allow comma and dot. For example it must allow:

0,0         


        

Answer 1

This will do what you want.

I've added whitespace and comments and parentheses to clarify it:

(                   #
  ( 0*[1-9]\d*   )  # a non-zero integer portion, followed by
  ( [\.,]\d{1,2} )? # an optional fraction of 1 or 2 decimal digits
)                   # 
|                   # OR
(                   #
  ( 0+ )            # a zero integer portion, followed by
  (                 # an mandatory non-zero 1-2 digit fraction, consisting of
    [\.,]           # a decimal point
    (               # followed by 
      ( 0[1-9]   )  # a 0 followed by a 1-9,
      |             # OR
      ( [1-9]\d? )  # a 1-9 followed by an optional decimal digit
  )
)

The regular expression is suboptimal it something like 0000000000.01 will backtrack when it doesn't find a non-zero digit following the zeros in the integer portion, but it should work.