正则表达式匹配数字，最多2位小数

Question

I'm writing a simple code in java/android.

I want to create regex that matches:

0
123
123,1
123,44

and slice everything after second digit after comma.

My first idea is to do something like that:

^\d+(?(?=\,{1}$)|\,\d{1,2})

 ^ - from begin
 \d+ match all digits
 ?=\,{1}$ and if you get comma at the end
 do nothin
 else grab two more digits after comma

but it doesn't match numbers without comma; and I don't understand what is wrong with the regex.

Answer 1

You may use

^(\d+(?:,\d{1,2})?).*

and replace with $1 . See the regex demo .

Details :

• ^ - start of string - (\\d+(?:,\\d{1,2})?) - Capturing group 1 matching:
  • \\d+ - one or more digits
  • (?:,\\d{1,2})? - an optional sequence of:
    • , - a comma
    • \\d{1,2} - 1 or 2 digits
• .* - the rest of the line that is matched and not captured, and thus will be removed.

Answer 2

Here:

,{1}

says: exactly ONE ","

Try:

,{0,1}

for example.

Answer 3

basic regex : [0-9]+[, ]*[0-9]+

In case you want to specify min max length use:

[0-9]{1,3}[, ]*[0-9]{0,2}