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Typedef in Dart Programming
In Dart, we make use of Typedef when we want to create an alias for a function type that we can use as type annotations for declaring variables and return types of that function type.
A typedef holds type information when a function type is assigned to a variable.
Syntax
typedef functionName(parameters)
We make use of the above syntax when we want to create a Typedef in Dart.
Now, let's take a look at an example when we want to assign a typedef variable to a function in a program.
typdef varName = functionName
Once we have assigned the functionName to a typedef variable, we can later invoke the original function with the help of the typedef variable name.
Consider the syntax shown below −
varName(parameters)
Example
Now, let's create an example in Dart where we will make use of a typedef variable, assign it different functions and later invoke the typedef variable with the varName.
Consider the example shown below −
typedef operation(int firstNo , int secondNo);
void add(int num1,int num2){
print("Sum of num1 + num2 is: ${num1+num2}");
}
void subtract(int num1,int num2){
print("Subtraction of num1 - num2 is: ${num1-num2}");
}
void main(){
operation op = add;
op(10,20);
op = subtract;
op(20,10);
}Output
Sum of num1 + num2 is: 30 Subtraction of num1 - num2 is: 10
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