I need regular expression for numbers that can be negative, with commas or decimal.
For examples: 12 +12 -12.0 -12,345.5466 +12,345,678,678 0.154
But not pass: "500." or "500,". I want that 500 will return as a number without the point or the comma that connect to the number.
The regular expression that I wrote is:
[-+]?((0|([1-9](\d*|\d{0,2}(,\d{3})*)))(\.\d*[0-9])?)(?!\S)
It is work at the correct numbers (like the examples), but It don't work for the '500,' or '500.'
Assuming you want to match 500 in 500. and 500,, you should bear in mind that (?!\S) requires a whitespace or end of string immediately to the right.
You may fix the problem with
[-+]?(?:0|[1-9](?:\d{0,2}(?:,\d{3})*|\d*))(?:\.\d+)?(?!\d)
See this regex demo, and note that this can be further enhanced depending on what contexts you need to exclude.
I replaced (?!\S) with (?!\d) at the end to fail the match if there is a digit, not any non-whitespace char, immediately on the right.
Note also that I removed unnecessary groups and converted all capturing groups to non-capturing.
Also, pay attention to the (?:,\d{3})*|\d*) group, where I swapped the alternatives since the first one is more specific and should go first.
Details
[-+]? - an optional - or +(?:0|[1-9](?:\d{0,2}(?:,\d{3})*|\d*)) - 0 or
[1-9] - a non-zero digit(?:\d{0,2}(?:,\d{3})*|\d*) - either
\d{0,2}(?:,\d{3})* - zero, one or two digits, and then zero or more occurrences of a comma and three digits| - or\d* - zero or more digits(?:\.\d+)? - an optional sequence of . and one or more digits(?!\d) - a negative lookahead that fails the match if there is a digit immediately to the right of the current location.