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
typedef GeeksForGeeks( int a, int b);
Geek1( int a, int b) {
print( "This is Geek1" );
print( "$a and $b are lucky geek numbers !!" );
}
Geek2( int a, int b) {
print( "This is Geek2" );
print( "$a + $b is equal to ${a + b}." );
}
void main()
{
GeeksForGeeks number = Geek1;
number(1,2);
number = Geek2;
number(3,4);
}
|
Output:
This is Geek1
1 and 2 are lucky geek numbers !!
This is Geek2
3 + 4 is equal to 7.
Note: Apart from this, typedef can also act as parameters of a function.
Example 2: Using typedef as a parameter of a function.
Dart
typedef GeeksForGeeks( int a, int b);
Geek1( int a, int b) {
print( "This is Geek1" );
print( "$a and $b are lucky geek numbers !!" );
}
number( int a, int b, GeeksForGeeks geek) {
print( "Welcome to GeeksForGeeks" );
geek(a, b);
}
void main()
{
number(21,23, Geek1);
}
|
Output:
Welcome to GeeksForGeeks
This is Geek1
21 and 23 are lucky geek numbers !!
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