Learning Exercise
A property in C# is a member of a class that provides access to data within that class. Callers can set or retrieve (get) the data. Properties can be either auto-implemented or have a backing field. They comprise a set accessor and/or a get accessor. In some other languages a "mutator" is roughly equivalent to a set accessor and an "accessor" is roughly equivalent to a get accessor although the composition of the syntax is completely different.
When setting a property the input value can be validated, formatted or otherwise manipulated and in fact any programmatic operation accessible to code in the class can be executed.
Similarly when retrieving a property data can be calculated or formatted and again any programmatic operation available to the class can be executed.
Properties have access modifiers (public, private etc.) in the same way as other
class members but the set accessor may have an access level independent of the retrieve (get)
accessor and vice versa. A property doesn't have to have both accessors, it can have just one (either get or set).
The basic syntax to express properties can take two forms:
private int myField;
public int MyProperty
{
get { return myField; }
set { myField = value; }
}
public int MyProperty { get; private set; } = 42;
Initialization is optional.
In this exercise you'll be modelling a weighing machine with Kilograms as a Unit.
You have 6 tasks each of which requires you to implement one or more properties:
To cater to different demands, we allow each weighing machine to be customized with a precision (the number of digits after the decimal separator).
Implement the WeighingMachine class to have a get-only Precision property set to the constructor's precision argument:
var wm = new WeighingMachine(precision: 3);
// => wm.Precision == 3
Implement the WeighingMachine.Weight property to allow the weight to be get and set:
var wm = new WeighingMachine(precision: 3);
wm.Weight = 60.5;
// => wm.Weight == 60.5
Clearly, someone cannot have a negative weight.
Add validation to the WeighingMachine.Weight property to throw an ArgumentOutOfRangeException when trying to set it to a negative weight:
var wm = new WeighingMachine(precision: 3);
wm.Weight = -10; // Throws an ArgumentOutOfRangeException
The tare adjustment can be any value (even negative or a value that makes the display weight negative)
Implement the WeighingMachine.TareAdjustment property to allow the tare adjustment to be set:
var wm = new WeighingMachine(precision: 3);
wm.TareAdjustment = -10.6;
// => wm.TareAdjustment == -10.6
After some thorough testing, it appears that due to a manifacturing issue all weighing machines have a bias towards overestimating the weight by 5.
Change the WeighingMachine.TareAdjustment property to 5 as its default value.
var wm = new WeighingMachine(precision: 3);
// => wm.TareAdjustment == 5.0
Implement the WeighingMachine.DisplayWeight property which should return a string showing the weight after tare adjustment, with the correct precision applied, and the unit added.
Note that:
display-weight = input-weight - tare-adjustment
var wm = new WeighingMachine(precision: 3);
wm.Weight = 60.567;
wm.TareAdjustment = 10;
// => wm.DisplayWeight == "50.567 kg"
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