Reliably Extracting String In Flutter List Every Time - flutter

Question

So I have a quite interesting exercise I've been trying to solve for a while now, but haven't come up with a reliable solution, so I thought you guys could help me out. I have this String that is composed of few random custom parts, for example:
"William\nWilliam description here...\n$170.00 usd") + Uuid().v4();
I need to extract the part after '$' and '.', in this case 170, but it can be any number between.
UPDATE
as I said in the last comment, if I wanted to do it in a function (find the price only), it could go something like this:
deleteSumItem(item) {
final regEx = RegExp(r'\$\d+(?:\.\d+)?');
const textToSearch = r'item';
final priceValueMatch = regEx.firstMatch(textToSearch);
print(priceValueMatch.group(0));
_totalPrice.remove(priceValueMatch);
_counter = _counter - priceValueMatch; //getting error here to convert to num
//but int.parse won't work either, then I get the String error
//RegExp can't be assigned to paremeter String
}
Also, this function returns null for regex, so there is some mistake I'm making, any thoughts?
deleteSumItem(item) {
final regEx = RegExp(r'\1\d+(?:\.\d+)?');
final priceValueMatch = regEx.firstMatch(r'item');
print('THIS IS REGEX: $priceValueMatch');} //priceValueMatch returns null
fix
deleteSumItem(item) {
RegExp regExp = RegExp(r'\^(\d+)\^');
String input = item;
String match = regExp.firstMatch("r" + '"' + input + '"').group(1);
print('Match: $match');
int number = int.parse(match);
print('Number: $number');
_totalPrice.remove(number);
_counter = _counter - number;}

Answer 1

Assuming you can answer 'yes' to the questions in my above comment, you can simply use regular expressions to find the price value in your string:
final regEx = RegExp(r'\$\d+(?:\.\d+)?');
const textToSearch = r'William\nWilliam description here...\n$170.00 cm';
final priceValueMatch = regEx.firstMatch(textToSearch);
print(priceValueMatch.group(0)); // this will print $170.00
The regular expression is looking for a dollar sign \$ followed by 1 or more digits d+ followed by optional decimal point and optional digits behind that decimal (?:\.\d+)?.
This actually ignores a lot of the questions in my above comment. This simply looks for a price value preceded by a dollar sign within the string you give it.
Here is another approach based on your comments. This is assuming the new line characters will always exist
const textToSearch = 'William\nWilliam description here...\n170.00 cm';
final lines = textToSearch.split('\n'); // Split on new line character
// If your template is always the same,
// then your number will be at the start of line 3:
print(lines[2]); // Will print: 170.00 cm
// If you want just your 170 value then:
final regEx = RegExp(r'\d+');
final priceValueMatch = regEx.firstMatch(lines[2]);
final priceInt = int.parse(priceValueMatch.group(0));
print(priceInt); // Will print: 170