Theoretical class Requirements

Classes whose instances will be stored in STL containers must have:

• a copy constructor
• operator=

If the instances will be sorted or compared then the class must have:

• operator==
• operator<

Practical class requirements

In practice, it may be necessary to please the compiler gods by defining some functions that are never called. The practical list of requirements is:

• a default constructor
• a copy constructor
• operator=
• operator==
• operator<