# Dart – Basics of Set

Set is a special type of collection in Dart programming. In which any object can occur only once. If we perform add operation in the set, if the object is already in the set then it will not add otherwise it will be added in the set.  dart: core library provides the Set class for implementation.

Syntax:  Identifier = new Set()

or

Identifier = new Set.from(Iterable)

Here, Iterable is the list of value which will be added in the set .

Example 1:

## Dart

 `void` `main() {  ` `   `  `   ``// create a new set number ` `   ``Set number = ``new`  `Set();  ` `   `  `   ``// add in the set  ` `   ``number.add(1);  ` `   ``number.add(2);  ` `   ``number.add(5); ` `   ``number.add(1);   ` `    `  `     `  `   ``// all elements are retrieved  ` `   ``// in the order in which  ` `   ``// they are inserted  ` `   ``for``(var no in number) {  ` `      ``print(no);  ` `   ``}  ` `} `

Output:

```1
2
5
```

Example 2:

## Dart

 `void` `main() { ` `   `  `   ``// Create a Set Number Which ` `   ``// contains a list of value ` `   ``Set number = ``new` `Set.from([1,11,14,11]);  ` `     `  `   ``// all elements are retrieved ` `   ``// in the order in which  ` `   ``// they are inserted  ` `   ``for``(var n in number) {  ` `      ``print(n);  ` `   ``}  ` `}`

Output:

```1
11
14
```

Example 3:

## Dart

 `void` `main() {  ` `   `  `   ``// Create a Set Number Which ` `   ``// contains a list of value ` `   ``Set number = ``new` `Set.from([``'geeks'``,``'for'``,``'geeks'``]);  ` `     `  `   ``// all elements are retrieved  ` `   ``// in the order in which  ` `   ``// they are inserted  ` `   ``for``(var n in number) {  ` `      ``print(n);  ` `   ``}  ` `}`

Output:

```geeks
for
```

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