Objects First

9.2 Class Design - Point Example

In this example, we examine a model for points in a 2-dimensional space. The class is called Point and contains methods to construct points from either cartesian (x,y) or polar (r,theta) coordinates. There's also a method to make a copy of a point, so that you can view this class as having three constructors!

The remaining methods are straightforward:

Name	Description
`XCoord( p )` `YCoord( p )` `RPolar( p )` `TPolar( p )`	Projectors for the: x-coordinate, y-coordinate, distance from origin, angle from origin
`Dist( p1, p2 )`	Distance between p1 and p2
`Displace( p1, delta )`	Displace p1 by delta
`Direction( p1, p2 )`	Direction from p1 to p2
`SetPoint( p, x, y )`	Set p to (x,y)
`SetPoint2( p, p1 )`	Set p to be the same as p1

The examples themselves:

Specification	Point.h
Implementation	Point.c

The observant among you will have noted some required features, such as pre-conditions, missing!

This has been a consequence of rushing this example to the market-place and is not an excuse for omitting them yourselves!

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