Dart how to add commas to a string number

Question

I\'m trying to adapt this: Insert commas into number string to work in dart, but no luck.

either one of these don\'t work:

print(\"1000200\".replaceAllMa         


        

Answer 1

You just forgot get first digits into group. Use this short one:

'12345kWh'.replaceAllMapped(new RegExp(r'(\d{1,3})(?=(\d{3})+(?!\d))'), (Match m) => '${m[1]},')

Look at the readable version. In last part of expression I added checking to any not digit char including string end so you can use it with '12 Watt' too.

RegExp reg = new RegExp(r'(\d{1,3})(?=(\d{3})+(?!\d))');
Function mathFunc = (Match match) => '${match[1]},';

List<String> tests = [
  '0',
  '10',
  '123',
  '1230',
  '12300',
  '123040',
  '12k',
  '12 ',
];

tests.forEach((String test) {
  String result = test.replaceAllMapped(reg, mathFunc);
  print('$test -> $result');
});

It works perfectly:

0 -> 0
10 -> 10
123 -> 123
1230 -> 1,230
12300 -> 12,300
123040 -> 123,040
12k -> 12k
12  -> 12 

Answer 2

Try the following regex: (\d{1,3})(?=(\d{3})+$)

This will provide two backreferences, and replacing your number using them like $1,$2, will add commas where they are supposed to be.