Regex to validate numbers before and after decimal excluding comma

1
votes

I am trying to validate decimal number of 13 digit before and 4 digit after dot excluding comma , i.e comma shouldn't be counted as a digit.

Valid Cases

1,234,567,890,123.1234

1234567890123.1234

123456789012.1234

1234567890123.123

12345.123

1.2

0

In Valid Cases

12345abc.23 // string or special characters  not allowed

1,234,567,890,1231.1234

1,234,567,890,123.12341

12345678901231.1234

1234567890123.12341

Current Regex

^[0-9]{1,13}(\.[0-9]{0,4})?$

The current Regex is counting comma as a digit.

Any help would be great.

2
regexvalidationmatching

2 Answers

1
votes

You could use a negative lookahead to assert what is directly on the right is not 14 times a digit before matching a dot:

^(?!(?:[^.\s\d]*\d){14})-?\d+(?:,\d{1,3})*(?:\.\d{1,4})?$

Explanation

  • ^ Start of string
  • -? Optional hyphen
  • (?! Negative lookahead, assert what follows is not
    • (?:[^.\s\d]*\d){14} Match not a digit, whitespace char or dot 14 times
  • ) Close lookahead
  • \d+ Match 1+ digits
  • (?:,\d{1,3})* Match comma, 1-3 digits and repeat 0+ times (Or use \d+)
  • (?:\.\d{1,3})? Optional part, match a dot and 1-4 digits
  • $ End of the string

Regex demo

0
votes

You could just specify the optional count of , Like

^[0-9]{0,1}([,])?[0-9]{0,3}([,])?[0-9]{0,3}([,])?[0-9]{1,3}(\.[0-9]{0,3})?$