main function
void
main()
Implementation
void main() {
print("Welcome to the circle calculator app:");
stdout.write("Please enter the radius of the circle: ");
String? radius = stdin.readLineSync();
// Convert the input, perform a multiplication operation, and then multiply by 3.1416
double? area = pow(double.parse(radius ?? "0"), 2) * 3.1416;
print("The area of the circle is: $area");
double? circumference = 2 * 3.1416 * (double.parse(radius ?? "0"));
print("The circumference of the circle is: $circumference");
print("Press any key to exit.");
stdin.readLineSync(); // Wait for user input before exiting
exit(0); // Exit the application
}