Assuming that we have the class animal, we can define some
variables that can be used to store animals. Remember that the class
is also a data type. We can also create some animals to put in
those variables. To create an animal, we use the syntax
classname(), i. e. the name of the class followed by a
pair of parentheses.
animal some_animal;
some_animal = animal();
animal my_dog = animal();
To access a member variable in an object, we use the syntax
object-expression->variable-name, i. e. the
object followed by the operator -> followed by the name of
the variable.
my_dog->name = "Fido";
my_dog->weight = 10.0;
some_animal->name = "Glorbie";
write("My dog is called " + my_dog->name + ".\n");
write("Its weight is " + my_dog->weight + ".\n");
write("That animal is called " + some_animal->name + ".\n");
Most objects need some initial values for its member variables. For
example, every animal needs a name and a weight. One way to handle
this is to set those variables separately, as we have done above. A
better way is to design the class in a way that lets it set the
variables immediately when an object is cloned from the class. You can
then give the values when cloning:
animal piglet = animal("Piglet", 6.3);
We can call a method in an object, with a similar "->"
syntax:
my_dog->eat("quiche"); // Real dogs eat quiche.
write("Its weight is now " + my_dog->weight + ".\n");
