CS-240

1
CS-240

• Classes (cont)
• Dick Steflik

2
Member functions

• Member functions of a class include
• getters
• used to retrieve state data
• setters
• used to set state data
• mutators
• used to modify state data
• functions that model the classes behavior
• tend to be action words (verbs or verb phrases)
• take_off , reverse_direction, open ...

3
Function prototypes

• Prototype are models of how a function is to be
  called
• are not necessarily part of the function
  definition, but may be
• float calculate_attack_angle (float, float)
• notice that in a prototype only the types are
  required, parameter names are not

4
Function signatures

• The signature of a function consists of
• returned type (if any)
• the function name
• the ordered set of types in the parameter list
• within its scope, a functions signature must be
  unique even if its name is overloaded

5
Parameters

• Parameters are required on a function definition
• parameter consists of a type and an identifier
• function formal parameters
• parameters in the function definition
• alias names for the actual arguments
• scope is local to the function
• parameters may be passed to a function
• by value
• by reference

ex. boolean exists(const point p)
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Value Parameters

• read only or input only parameters
• makes a local copy (on the stack) of the value
  for use in the function copies value of argument
  before running the function
• pass by value
• slower than pass by reference
• use only for small objects

7
Reference Parameters

• read/write parameter value of argument can be
  changed
• uses address of argument to manipulate it
• doesnt require local storage
• use to identify reference parameters
• remember is the address operator

ex. void rotate (point p)
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Reference Parameters (cont.)

• use const reference parameters instead of value
  parameters (faster), less memory rqd.
• const indicates a promise to not modify the
  reference parameter exists

ex. double distance(const point p)
p is passed by reference as an input only
parameter
9
Inlining functions

• Two ways
• inline keyword (place on function definition
  line) replaces a call to the function with a
  copy of the functions code.
• defining the function in the class definition
  automatically makes it inline
• use for small functions
• many calls to the function will bloat the program
• slightly faster than a regular function call

10
Function Overloading

• The function name may be reused (overloaded)
  within a class
• each definition must have a unique signature
  (pattern made up of function name and the
  parameter types)