Typedef in Dart
Typedef in Dart is used to create a user-defined identity (alias) for a function, and we can use that identity in place of the function in the program code. When we use typedef we can define the parameters of the function.
Syntax: typedef function_name ( parameters );
With the help of typedef, we can also assign a variable to a function.
Syntax:typedef variable_name = function_name;
After assigning the variable, if we have to invoke it then we go as:
Syntax: variable_name( parameters );
By this we will be able to use a single function in different ways:
Example 1: Using typedef in Dart.
Dart
// Dart program to show the usage of typedef // Defining alias name typedef GeeksForGeeks( int a, int b); // Defining Geek1 function Geek1( int a, int b) { print( "This is Geek1" ); print( "$a and $b are lucky geek numbers !!" ); } // Defining Geek2 function Geek2( int a, int b) { print( "This is Geek2" ); print( "$a + $b is equal to ${a + b}." ); } // Main Function void main() { // Using alias name to define // number with Geek1 function GeeksForGeeks number = Geek1; // Calling number number(1,2); // Redefining number // with Geek2 function number = Geek2; // Calling number number(3,4); } |
Output:
This is Geek1 1 and 2 are lucky geek numbers !! This is Geek2 3 + 4 is equal to 7.
Note: Apart from this, typedef can also act as parameters of a function.
Example 2: Using typedef as a parameter of a function.
Dart
// Dart program to show the usage of typedef // Defining alias name typedef GeeksForGeeks( int a, int b); // Defining Geek1 function Geek1( int a, int b) { print( "This is Geek1" ); print( "$a and $b are lucky geek numbers !!" ); } // Defining a function with a typedef variable number( int a, int b, GeeksForGeeks geek) { print( "Welcome to GeeksForGeeks" ); geek(a, b); } // Main Function void main() { // Calling number function number(21,23, Geek1); } |
Output:
Welcome to GeeksForGeeks This is Geek1 21 and 23 are lucky geek numbers !!
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