Regular expression for Zero value or null value

c开发者_开发技巧an someone tell me the regular expression which will check if value is 0.0 or 00.00 and that it is a positive value.

This should work:

/^0*(\.0+)$?/

0        -> true
.0       -> true
.000     -> true
.001     -> false
.01      -> false
1.0000   -> false
0.000000 -> true
1.1100   -> false

Note: this regex assumes there are no constructs like +0.00; if you need something like that, use this: /^\+?0*(\.0+)$?/. Also, if you ask me, you should the parseFloat(str) === 0.0 equivalent for your language.

/^\+?0+(\.0+)?$/

should do the trick.

(I know 0's can't be positive or negative, but I feel it's good to check for a positive sign just in case)

This will match exactly 0.0 and 00.00 as requested. But it's a good idea to check on an undefined amount of zero's as described in other answers.

/^0{1,2}\.0{1,2}$/

Can't really say this is any better than what's already presented, but it's a different approach:

 $r = "^[^-0.]"
 "0.0" -notmatch $r
 "00.00" -notmatch $r
 "-1" -notmatch $r
 "1" -notmatch $r

 True
 True
 True
 False