Function Syntax

1. Defining a Function with No Parameters and No Return Type

To define such a function, you use the void return type and leave the parameter list empty:

Syntax

Example

Here’s an example of a function named printMessage that prints a message to the console:

Using the Function

To call this function, simply use its name followed by parentheses:

Full Example in a Dart Program

Here’s the complete code to define and call a function with no parameters and no return type:

Summary

• Function Definition: Use void to indicate no return type and empty parentheses to indicate no parameters.
• Parameters : Define the type and name of each parameter inside the parentheses.
• Function Body : Contains the code to be executed when the function is called.
• Function Call : Use the function name followed by parentheses, passing arguments corresponding to the parameters.

2. Defining a Function with Parameters and No Return Type

To define a function that takes parameters and does not return a value, you use the void return type. You also specify the parameter types and names within the parentheses.

Syntax

Example

Let's create a function named printDetails that takes two parameters: a String parameter name and an int parameter age, and prints out a message.

Explanation

Function Definition:

void printDetails(String name, int age): This defines a function named printDetails that takes two parameters (name of type String and age of type int) and does not return a value (void).

Function Call:

printDetails('Alice', 30): Calls the printDetails function with the arguments 'Alice' and 30, printing Name: Alice, Age: 30.

printDetails('Bob', 25): Calls the printDetails function with the arguments 'Bob' and 25, printing Name: Bob, Age: 25.

Summary

• Function Definition: Use void to indicate no return type and specify parameters inside the parentheses.
• Parameters : Define the type and name of each parameter.
• Function Body : Contains the code to be executed when the function is called.
• Function Call : Use the function name followed by parentheses and pass arguments corresponding to the parameters.

3. Defining a Function with No Parameters and a Return Type

To define such a function, you specify the return type, the function name, and leave the parameter list empty. The function should return a value of the specified return type.

Syntax

Example

Here’s an example of a function named getGreeting that returns a greeting message as a String:

Explanation

Using the Function

To call this function and use its return value, you can do something like this in the main function:

Full Example in a Dart Program

Here’s the complete code to define and call a function with no parameters and a return type:

Summary

• Function Definition: Specify the return type, function name, and leave the parameter list empty.
• Return Statement: The function body should include a return statement that returns a value of the specified return type.
• Function Call : Use the function name followed by empty parentheses to invoke it and handle the returned value appropriately.

4. Defining a Function with Parameter And Return Type

To define and use a function in Dart that has parameters and a return type, you specify the return type, function name, parameters, and include a return statement in the function body. Here’s how you do it:

Syntax

Example

Here's an example of a function named add that takes two integers as parameters and returns their sum:

Using the Function

To call this function, you use its name followed by parentheses and pass the required arguments. You can then capture the returned value:

Full Example in a Dart Program

Here’s the complete code to define and call a function with parameters and a return type:

Explanation

Function Definition:

int add(int a, int b): Defines a function named add that takes two int parameters (a and b) and returns an int.

return a + b;: Returns the sum of a and b.

Function Call:

int sum = add(5, 3);: Calls the add function with the arguments 5 and 3, and stores the result in the variable sum.

print('The sum is $sum');: Prints the result.

Summary

• Function with Parameters: Takes inputs to operate on.
• Function with Return Type: Returns a value after execution.
• Usage : Call the function with appropriate arguments and handle the returned value.