Flutter Dart: How to extract a number from a string using RegEx

Question

I want to extract a number (integer, decimal or 12:30 formats) from a string. I have used the following RegEx but to no avail:

final RegExp numberExp = new RegExp(
      "[a-zA-Z ]*\\d+.*",
      caseSensitive: false,
      multiLine: false
    );
final RegExp numberExp = new RegExp(
      "/[+-]?\d+(?:\.\d+)?/g",
      caseSensitive: false,
      multiLine: false
    );
String result = value.trim();
result = numberExp.stringMatch (result);
result = result.replaceAll("[^0-9]", "");
result = result.replaceAll("[^a-zA-Z]", "");

So far, nothing works perfectly.

Any help appreciated.

Günter Zöchbauer · Accepted Answer · 2018-12-04 18:10:38Z

11

const text = '''
Lorem Ipsum is simply dummy text of the 123.456 printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an 12:30 unknown printer took a galley of type and scrambled it to make a
23.4567
type specimen book. It has 445566 survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
''';

final intRegex = RegExp(r'\s+(\d+)\s+', multiLine: true);
final doubleRegex = RegExp(r'\s+(\d+\.\d+)\s+', multiLine: true);
final timeRegex = RegExp(r'\s+(\d{1,2}:\d{2})\s+', multiLine: true);
void main() {
  print(intRegex.allMatches(text).map((m) => m.group(0)));
  print(doubleRegex.allMatches(text).map((m) => m.group(0)));
  print(timeRegex.allMatches(text).map((m) => m.group(0)));
}

answered Dec 4, 2018 at 18:10

Günter Zöchbauer

661k235 gold badges2.1k silver badges1.6k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Yadhu Over a year ago

hello,why this fails when the the integer is like this570009, I mean when there is no space between the String and the int, as well as why does this only work when the string starts from 2nd line?

Günter Zöchbauer Over a year ago

Because the regexp in my answer specifically skips only spaces at the beginning/end (\s). You probably want something like r'.*?(\d*).*' or r'[^0-9]*([0-9]*).*'. I haven't tested these examples and I don't do Regexp much, so be wary. (only on my phone)

Andrey Gordeev · Accepted Answer · 2020-09-17 06:47:31Z

4

For one-line strings you can simply use:

final intValue = int.parse(stringValue.replaceAll(RegExp('[^0-9]'), ''));

answered Sep 17, 2020 at 6:47

Andrey Gordeev

32.7k16 gold badges143 silver badges169 bronze badges

Comments

Ullaakut · Accepted Answer · 2019-06-16 15:31:18Z

3

That's how I solved my problem:

bool isNumber(String item){
    return '0123456789'.split('').contains(item);
}

List<String> numbers = ['1','a','2','b','3','c','4','d','5','e','6','f','7','g','8','h','9','i','0'];
print(numbers);
numbers.removeWhere((item) => !isNumber(item));
print(numbers);

And here's the output:

[1, a, 2, b, 3, c, 4, d, 5, e, 6, f, 7, g, 8, h, 9, i, 0]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 0]

edited Jun 16, 2019 at 15:31

Ullaakut

3,7743 gold badges24 silver badges36 bronze badges

answered Jun 16, 2019 at 11:04

M. Massula

4,9502 gold badges15 silver badges17 bronze badges

Comments

Mubashar · Accepted Answer · 2022-03-31 09:38:08Z

-1

Try this for phone numbers starting with +country code detection in a multiline string.

\b[+][(]{0,1}[6-9]{1,4}[)]{0,1}[-\s.0-9]\b

answered Mar 31, 2022 at 9:38

Mubashar

71 bronze badge

Collectives™ on Stack Overflow

Flutter Dart: How to extract a number from a string using RegEx

4 Answers 4

2 Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related