I want to use Dart for…in loop in this function but I keep facing this error even though I declared the arr as an Iterable<int>
function:
void sumOfTwoNumbers(int targetSum, Iterable<int> arr) {
for (int i in arr.length-1) {
//stuff
}
}
It's working with a normal for loop though, I don't know how can I fix this, for any help that would be appreciated
Because arr.length you are trying to iterate over a int
arr is of type Iterable which is expected on the statement:
for (var T element in Iterable<T>) { /* ... */ }
So:
void sumOfTwoNumbers(int targetSum, Iterable<int> arr) {
for (int i in arr) {
//stuff
}
}
And if you want to remove the last element, just create another list from your original list that takes only the first N - 1 elements, to do that you can use take from Iterable API:
Note: in this case if your array is empty the length will be zero which results in 0 - 1 -> -1 which throws a
RangeErrorto avoid it you can usemax()fromdart:mathAPI
void sumOfTwoNumbers(int targetSum, Iterable<int> arr) {
// Iterable over all elements except by the last one
for (int i in arr.take(arr.length - 1)) {
//stuff
}
}
By using max():
import 'dart:math';
void sumOfTwoNumbers(int targetSum, Iterable<int> arr) {
// Iterable over all elements except by the last one
for (int i in arr.take(max(arr.length - 1, 0))) {
//stuff
}
}
Same rule applies if you want skip the first element, you can use the skip API either:
void sumOfTwoNumbers(int targetSum, Iterable<int> arr) {
// Iterable over all elements except by the first one by skipping it
for (int i in arr.skip(1)) {
//stuff
}
}
Take a look at Dart codelabs/iterables it can help you understand better how collections, lists and iterables works in Dart.
for (int i in arr-1) it keep giving an error