In dart language, I want to check if this array element=[1,1] exists in this array
list=[[0, 3], [0, 4], [1, 0], [1, 1], [1, 2], [1, 3]]
and give me the exact position if it does(3 in this case).
I tried indexOf but it doesn't work, always returns -1
You can use this function:
int isInList(List<List<dynamic>> list, List<dynamic> element) {
for (int i = 0; i < list.length; i++) {
var e = list[i];
if (e.length == element.length) {
bool rejected = false;
for (int j = 0; j < e.length; j++) {
if (e[j] != element[j]) {
rejected = true;
}
}
if (!rejected) {
return i;
}
}
}
return -1;
}
the problem is you have a list of lists and indexOf won't compare elements of inner lists.
You can use indexWhere() to get the position of the item. And you should consider that you're trying to find a list in a list. Your expected list contains two items. So you can search it on the given list like this:
var list = [
[0, 3],
[0, 4],
[1, 0],
[1, 1],
[1, 2],
[1, 3]
];
var element = [1, 1];
var index = list.indexWhere(
(el) => el.first == element.first && el.last == element.last);
print(index); // output will 3
Thanks to @pskink, you can also use listEquals method with importing the package.
import 'package:flutter/foundation.dart';
///...
var s = list.indexWhere((el) => listEquals(el, element));
print(s);
final b = [1, 1]; final index = list.indexWhere((a) => listEquals(a, b)); print(index);