Dart Anonymous Functions (original) (raw)

Last Updated : 28 Mar, 2025

An **anonymous **function in **Dart is like a named function but they do not have names associated with it. An **anonymous function can have zero or more parameters with optional type annotations. An **anonymous function consists of self-contained blocks of code and that can be passed around in our code as a function parameter.

In Dart most of the functions are named functions we can also create nameless function knows as an anonymous function, lambda, or closure.
In Dart, we can assign an anonymous function to constants or variables; later, we can access or retrieve the value of closure based on our requirements:

**Syntax:

(parameter_list) {
statement(s)
}

Anonymous Function in forEach()

**Example:

Dart `

// Dartprogram to illustrate // Anonymous functions in Dart void main() { var list = ["Shubham","Nick","Adil","Puthal"]; print("GeeksforGeeks - Anonymous function in Dart"); list.forEach((item) { print('${list.indexOf(item)} : $item'); }); }

**Output:

GeeksforGeeks - Anonymous function in Dart
0 : Shubham
1 : Nick
2 : Adil
3 : Puthal

This example defines an anonymous function with an untyped parameter, item. The function, invoked for each item in the list, prints a string that includes the value at the specified index.

Assigning an Anonymous Function to a Variable

In Dart, functions are treated as first-class objects, allowing us to assign an anonymous function to a variable and use it like a regular function.

**Example:

Dart `

void main() { // Assigning an anonymous function to a variable var multiply = (int a, int b) { return a * b; };

print(multiply(5, 3)); // Output: 15

}

**Output:

Using an Anonymous Function as a Callback

Anonymous functions are widely used in **asynchronous operations like button clicks or API calls.

**Example:

Dart `

void performOperation(int a, int b, Function operation) { print('Result: ${operation(a, b)}'); }

void main() { // Passing an anonymous function performOperation(4, 2, (a, b) => a + b); }

**Output:

Result: 6