In Dart, a **`set`** is a particular instance of a list in which all of the elements are unique.

>If there are duplicates, the set only keeps the first instance. For example,
`{'Tom','Alsvin','Eddie','Tom'}` results in `{'Tom','Alsvin','Eddie'}`

The **`length` function** in Dart for sets returns the number of elements in a set. In short, this function is used to get the current size of a set. 

> `dart:core` is required in-order to use this function.

Figure 1 shows the visual representation of the `length` function:

#   
#  Syntax
```dart
int set_name.length
// where the set_name is the name of the set
```
# 
#  Parameter
This function does not require a parameter.
##
## Return value
This function returns the number of elements in a set and is used to get the current size of a set.


##
## Code
The following code shows how to use `set.length` function in Dart:

import 'dart:convert';
import 'dart:core';
void main() {
  Set<String> set_1 = {'Tom','Alsvin','Eddie'}; 
  //set containing unique value
  print("set_1 length: ${set_1.length}");

  //empty set
  Set<String> set_2 = {};
  print("set_2 length: ${set_2.length}");

  //set containing non-unique value
  Set<String> set_3 = {'Tom','Alsvin','Eddie','Tom'}; 
  print("set_3 length: ${set_3.length}");

}

What is the set.length method in Dart?

The length method in Dart returns the number of unique elements in a set, indicating its current size.