Dart: Use regexp to remove whitespaces from string

Question

I am attempting to remove all white spaces from a string using Dart and Regexp. Given the following string: "test test1 test2" I would want to get: "testtest1test2". I have read some examples in javascript but they do not seem to work in Dart. These are some attempts so far:

print("test test1 test2".replaceAll(new RegExp(r"/^\s+|\s+$|\s+(?=\s)/g"), ""));
print("test test1 test2".replaceAll(new RegExp(r"/\s+\b|\b\s/ig"), ""));

This is based off: Regex to remove whitespaces

Can someone advise where I am going wrong with this.

I think if you simply want to remove all whitespace it should be: print("test test1 test2".replaceAll(new RegExp(r"\s+"), "")); — sniperd
– sniperd, Commented Aug 24, 2017 at 15:55

Erik B · Accepted Answer · 2019-03-27 19:19:09Z

16

I think this covers more bases: textWithWhitespace.replaceAll(new RegExp(r"\s+\b|\b\s|\s|\b"), "")

The current accepted answer was not working for me. In the case where it was all whitespace, my whitespace was not removed

String whitespace = "    ";
print(whitespace.replaceAll(new RegExp(r"\s\b|\b\s"), "").length);
//length is 4 here

answered Mar 27, 2019 at 19:19

Erik B

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Comments

Robouste · Accepted Answer · 2019-06-11 09:17:42Z

9

I couldn't believe that it was so complex to simply remove whitespaces from a string. So I came up with this solution, which I like much more than playing with regex:

myString.split(" ").join("");

answered Jun 11, 2019 at 9:17

Robouste

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1 Comment

Shaun Ramsey Over a year ago

This removes spaces and not all whitespaces. It may also be a costly performance wise, although I have not given it a fair testing.

Shmuel Levinson · Accepted Answer · 2020-12-16 08:11:26Z

5

str.replaceAll(new RegExp("[ \n\t\r\f]"), '');

This removes all whitespace (\t \r \n \f) which matches a space, a tab, a carriage return, a line feed or a form feed as seen here https://www.regular-expressions.info/shorthand.html#:~:text=%5Cs%5Cd%20matches%20a%20whitespace,latter%20matches%201%20(one)

String s1 = " have Yourself \n \t A M e r\r \r \f r   y  Little Christma s    ";
print(s1.replaceAll(new RegExp("[ \n\t\r\f]"), '')); 
//haveYourselfAMerryLittleChristmas

The second example demonstrates that a string which is all whitespace has length zero after applying the replaceAll.

String whiteSpacesOnly = "   \t \n \r \f";
print(whiteSpacesOnly.replaceAll(new RegExp("[ \n\t\r\f]"), '').length); 
//0

edited Dec 16, 2020 at 8:11

answered Dec 16, 2020 at 8:02

Shmuel Levinson

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Comments

lrn · Accepted Answer · 2017-08-25 09:23:57Z

4

print("test test1 test2".replaceAll(new RegExp(r"\s+\b|\b\s"), ""));

(without /ig) worked for me. These options are not supported in Dart this way.

/g is equivalent to All in replaceAll
/i is equivalent to new RegExp(r"...", caseSensitive: false)

edited Aug 25, 2017 at 9:23

lrn

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answered Aug 24, 2017 at 15:57

Günter Zöchbauer

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3 Comments

SSS Over a year ago

Thanks - that explains what I was doing wrong! I see this works just for single space gaps - do you know what I should add to make it work for varying length space gaps? e.g. "test test1 test2"

Günter Zöchbauer Over a year ago

I assume what sniperd posted below your question should do what you want.

BIS Tech Over a year ago

@GünterZöchbauer check this.. this is not work this is not work.. try this one String name = '4 ever 1 k g @@ @'; print(name.replaceAll(new RegExp(r"\s+\b|\b\s"), ""));

intraector · Accepted Answer · 2019-12-12 12:52:26Z

4

This works fine even without using RegExp:

myString.replaceAll(" ", "");

answered Dec 12, 2019 at 12:52

intraector

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Comments

H Zan · Accepted Answer · 2019-09-17 05:29:48Z

1

whitespace.replaceAll(new RegExp(r"\ "), ""); This is ok for me.

answered Sep 17, 2019 at 5:29

H Zan

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Matthew Trent · Accepted Answer · 2021-05-05 06:30:33Z

This isn't an exact answer to the question. However, it's the answer I needed when I stumbled upon this problem earlier today.

The following code converts a String with random spaces (even multiple spaces) all throughout it to a String that only has single spaces between each word (it removes spaces on the outsides too).

For example, this could be good for when your user chooses a username for your application and decides to be a goof and enters " Mr Bob Felix Johnson " instead of "Mr Bob Felix Johnson".

void main() {
  // INPUT NAME WITH UNWANTED SPACES
  String text = '  Mr  Bob Felix    Johnson     ';
  // INPUT NAME WITH UNWANTED SPACES
  final pattern = RegExp('\\s+');
  text = text.replaceAll(pattern, ' ');
  if (text[0] == ' ') {
    text = text.substring(1, text.length);
  }
  if (text[text.length - 1] == ' ') {
    text = text.substring(0, text.length - 1);
  }
  // NAME WITH REMOVED SPACES
  print(text); // THIS PRINTS "Mr Bob Felix Johnson"
  // NAME WITH REMOVED SPACES
}

UlanNurmatov · Accepted Answer · 2021-07-12 13:39:55Z

0

In addition to Matthew Trent's solution here https://stackoverflow.com/a/67396167/12411655

Instead of this

if (text[0] == ' ') {
    text = text.substring(1, text.length);
  }
  if (text[text.length - 1] == ' ') {
    text = text.substring(0, text.length - 1);
  }

you can just use trim() method like this

text.trim().replaceAll(RegExp('\\s+'), ' ');

answered Jul 12, 2021 at 13:39

UlanNurmatov

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Comments

Danial Hussain · Accepted Answer · 2021-12-03 14:27:09Z

-2

mysecond = myString.trim() works for me :)

answered Dec 3, 2021 at 14:27

Danial Hussain

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1 Comment

Suraj Rao Over a year ago

This will only remove preceding and trailing whitespaces though. Not anything in the middle of the string

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