Related Articles

# Dart – Fat Arrow Notation

• Last Updated : 07 Sep, 2021

In Dart, we have fat arrow notation ( => ).  A fat arrow is used to define a single expression in a function. This is a cleaner way to write functions with a single statement.

Declaring Fat arrow expression in dart –

Syntax :

`ReturnType FunctionName(Parameters...) => Expression;`

In the above syntax:

• ReturnType consists of datatypes like void,int,bool, etc..
• FunctionName defines the name of the function.
• Parameters are the list of parameters function requires.

Let’s see how we can write the below code in a more short way.

## Dart

 `void` `main() {``   ` `  ``perimeterOfRectangle(47, 57);``  ` `}` `void` `perimeterOfRectangle(``int` `length, ``int` `breadth) {``  ``var perimeter = 2 * (length + breadth);``  ``print(``'The perimeter of rectangle is \$perimeter'``);``}`

Output:

`The perimeter of rectangle is 208`

When the body of the function contains only one line, you can omit the curly braces and the return statement in favor of the “arrow syntax” as shown below:

## Dart

 `void` `main() {``  ``perimeterOfRectangle(47, 57);`` ``}` `// Arrow Syntax``void` `perimeterOfRectangle(``int` `length, ``int` `breadth) =>``  ``print(``'The perimeter of rectangele is \${2 * (length + breadth)}'``);`

Output:

`The perimeter of rectangele is 208`

If we compare the above code we got the same output with much less code using Fat arrow notation.

Example 1:

Consider the below code:

## Dart

 `void` `sum (``int` `x, ``int` `y) {``  ` `  ``// printing the result``  ``print( ``'sum is \${x + y}'``);``}` `void` `main (){``  ``sum(5,2);``}`

Output:

`sum is 7`

The given functions can be optimized with the help of a fat arrow in Dart and the same output we can get:

## Dart

 `void` `main(){``  ``sum(2,5);``}` `// Arrow Syntax``void` `sum(``int` `x,``int` `y) => print(``'sum is \${ x + y}'``);`

Output:

`sum is 7`

### Points to remember:

• Fat arrow is a clean way to write function expression in a single line.
• Fat arrow notation doesn’t have statements body ‘ { } ‘ .
• The statement body is replaced with   ‘ => ‘ fat arrow which points to a single statement.

My Personal Notes arrow_drop_up