I don't found how to add variable in a regex
for example I have a String who is an output of list
MyString ="list:[2020-09-05 12:23, 2020-09-04 12:23]"
I use regex to extract date match = 2020-09-05
But I don't found how to add this match variable in other regex area expression, like that:
RegExp regExp = new RegExp(
r'((Prefix$match)[1-9]\S(,suffix))',);
If your list is filled with those types of elements, I would use
var element = string.splits(' ').first;
Related
I am trying to get string using RegEx; here is the string:
window.runParams = {};
window.runParams = {blablabla};
How to get the second string {blablabla}? I am using REGEX:
(?<=window.runParams = ").*(?=;)
But that gets the first string {}.
If you want to get string with braces eg: {blablabla}
window.runParams = ({\w+})
If you want to get only the string inside braces eg: blablabla
window.runParams = {(\w+)}
Value of group 1 is your result
The following pattern captures only curly brackets with word character content:
(?<=window.runParams = ){\w+}(?=;)
and will only capture:
{blablabla}
when run against the text:
window.runParams = {};
window.runParams = {blablabla};
See results here:
https://regex101.com/r/mTwA64/1
try modifying your regex so it only accepts matches with non-empty curly brackets \{.+\} such as
(?<=window\.runParams = )(\{.+\})(?=;)
...there's probably ways to simplify the regex further, depending on you problem...my guess is you don't need the lookahead/lookbehind, e.g. in the example given \{.+\} will do just fine (returns {blablabla}) ....but it really depends on the format and content of your file...also remember braces, dots etc have a special meaning in regexes so you probably would want to escape them
I'm trying to parse in Dart long strings containing hashtags, so far I tried various combinations with regexp but I cannot find the right use.
My code is
String mytestString = "#one #two, #three#FOur,#five";
RegExp regExp = new RegExp(r"/(^|\s)#\w+/g");
print(regExp.allMatches(mytestString).toString());
The desidered output would be a list of hahstags
#one #two #three #FOur #five
Thankyou in advance
You should not use a regex literal inside a string literal, or backslashes and flags will become part of the regex pattern. Also, omit the left-hand boundary pattern (that matches start of string or whitespace) if you need to match # followed with 1+ word chars in any context.
Use
String mytestString = "#one #two, #three#FOur,#five";
final regExp = new RegExp(r"#\w+");
Iterable<String> matches = regExp.allMatches(mytestString).map((m) => m[0]);
print(matches);
Output: (#one, #two, #three, #FOur, #five)
String mytestString = "#one #two, #three#FOur,#five";
RegExp regExp = new RegExp(r"/(#\w+)/g");
print(regExp.allMatches(mytestString).toString());
This should match all of the hashtags, placing them into capture groups for you to later use.
If I search a string for matches to a regex which is the union of two or more sub-regexen, is there any way to determine which sub-regex matches without checking each of them individually?
For example, if I have the code:
var regExp = new RegExp('ab|cd');
var matches = regExp.allMatches('absolutely fabulous');
the search returns two matches - but is there a way for me to know which match corresponds to which sub-regex?
Found an answer thanks to searching for branches.
var regExp = new RegExp('(ab)|(cd)'); //brackets are significant
var matches = regExp.allMatches('absolutely fabulous');
var m1 = match.first;
print(m1.group(1)); // 'ab'
print(m1.group(2)); // null, since second term (cd) not matched here
var m2 = match.last;
print(m2.group(1)); // null, since first pattern not matched here
print(m2.group(2)): // 'ac'
Other useful info at
dart regex matching and get some information from it
I'm trying to get my Dart web app to: (1) determine if a particular string matches a given regex, and (2) if it does, extract a group/segment out of the string.
Specifically, I want to make sure that a given string is of the following form:
http://myapp.example.com/#<string-of-1-or-more-chars>[?param1=1¶m2=2]
Where <string-of-1-or-more-chars> is just that: any string of 1+ chars, and where the query string ([?param1=1¶m2=2]) is optional.
So:
Decide if the string matches the regex; and if so
Extract the <string-of-1-or-more-chars> group/segment out of the string
Here's my best attempt:
String testURL = "http://myapp.example.com/#fizz?a=1";
String regex = "^http://myapp.example.com/#.+(\?)+\$";
RegExp regexp= new RegExp(regex);
Iterable<Match> matches = regexp.allMatches(regex);
String viewName = null;
if(matches.length == 0) {
// testURL didn't match regex; throw error.
} else {
// It matched, now extract "fizz" from testURL...
viewName = ??? // (ex: matches.group(2)), etc.
}
In the above code, I know I'm using the RegExp API incorrectly (I'm not even using testURL anywhere), and on top of that, I have no clue how to use the RegExp API to extract (in this case) the "fizz" segment/group out of the URL.
The RegExp class comes with a convenience method for a single match:
RegExp regExp = new RegExp(r"^http://myapp.example.com/#([^?]+)");
var match = regExp.firstMatch("http://myapp.example.com/#fizz?a=1");
print(match[1]);
Note: I used anubhava's regular expression (yours was not escaping the ? correctly).
Note2: even though it's not necessary here, it is usually a good idea to use raw-strings for regular expressions since you don't need to escape $ and \ in them. Sometimes using triple-quote raw-strings are convenient too: new RegExp(r"""some'weird"regexp\$""").
Try this regex:
String regex = "^http://myapp.example.com/#([^?]+)";
And then grab: matches.group(1)
String regex = "^http://myapp.example.com/#([^?]+)";
Then:
var match = matches.elementAt(0);
print("${match.group(1)}"); // output : fizz
I want to extract a portion of a string, allowing for the dash character to appear randomly throughout. In my match, I want the dash character occurrences to be included.
Let's say I have a scenario like so:
haystack = "arandomse-que-nce"
needle = "sequence"
and I want to come out on the other end with a string like se-que-nce this this case, what would the regex pattern look like?
I would split the string and then join by -*; for example, in JavaScript:
var needle = "sequence"
var regex = new RegExp(needle.split('').join('-*'))
var result = "arandomse-que-nce".match(regex) // ["se-que-nce"]
var result2 = "a-bad-sequ_ence".match(regex) // null
You could also use a regex to insert -* between each character:
var regex = new RegExp(needle.replace(/(?!$|^)/g, '-*'))
Both the split/join method and the replace method return 's-*e-*q-*u-*e-*n-*c-*e' for the regex.
If you have characters like * in your string, that have meanings in regular expressions, you may want to escape them, like so:
var regex = new RegExp(needle.replace(/(?!$|^)/g, '-*')
.replace(/([-\\^$*+?.()|[\]{}])/g, '\\$1'))
Then, if needle was 1+1, for example, it would give you 1-*\+-*1 for the regex.
s-*e-*q-*u-*e-*n-*c-*e-*
The assumes that multiple hyphens in a row are okay.
EDIT: Doorknob's split/join solution is good, but be aware that it only works for character that aren't special characters (*, +, etc.)
I don't know what the specifications are, but if there are special characters, make sure to escape them:
new RegExp(needle.split('').map(function(c) { return '\\' + c; }).join('-*'))
You could try to use:
s-?e-?q-?u-?e-?n-?c-?e