In Unified Modeling Language (UML) class diagrams, an attribute
represents a data definition for an instance of a classifier. An attribute
describes a range of values for that data definition.
A classifier can have any number of attributes or none at all. Attributes describe the structure and value of an instance of a class.
For example, one of the attributes that a "Customer" class has is a "balance" attribute that holds the amount of money in the customer's account.
In UML class diagrams, the following mappings exist:
- C/C++ fields map to attributes,
- C/C++ primitive types always map to attributes,
- C/C++ attributes can be shown as associations, except primitive types (int, float, char, and so on).
Attributes are shown in the attribute compartment of a shape.
The following table shows attributes declared in source code and how they are illustrated in the Visualizer.
| C/C++ source code | UML visualization |
 |
 |
You can show, hide, or collapse the attribute compartment, and show or
hide the compartment title. You can also specify the visibility styles of
attributes as text symbols (such as "-") or icons (such as 
).