Flutter getting string between special characters using RegEx

Question

I have string like this one ==here==. How can I get here using RegEx pattern.

I know I can use .substring like

    const pattern = "==";
    const str = "==here==";
    final start = str.indexOf(pattern) + pattern.length;
    final end = str.lastIndexOf(pattern);

    final sub = str.substring(start, end);

    expect(sub, 'here');

for this but I want to use regex pattern so that I could get first match correctly.

What I want exactly is to get first string that is wrapped in two == even if there are thousand matches.

lrn · Accepted Answer · 2022-03-04 10:11:56Z

1

The simplest RegExp just matches ==(something)== and uses the capture. Here it uses a non-greedy match so that it finds the first following ==.

var re = RegExp(r'==([^]*?)==');
var sub = re.firstMatch(str)?[1];

If you need the RegExp match itself to be the string between the ==s, you can use look-behind and look-ahead:

var re = RegExp(r'(?<===)[^]*?(?===)');
var sub = re.firstMatch(str)?[0];

answered Mar 4, 2022 at 10:11

lrn

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Maryam K · Accepted Answer · 2022-03-04 10:21:09Z

0

String find(String str) {
RegExp exp = RegExp(r'==([^]*?)==');
RegExpMatch? match = exp.firstMatch(str);
return match?.group(1) ?? '';

}

answered Mar 4, 2022 at 10:21

Maryam K

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