Question

The purchase class contains a readonly property named tax. the property is associated with the private dbltax variable. a button's click event procedure instantiates a purchase object and assigns it to the currentsale variable. which of the following is valid in the click event procedure?

A) currentSale.Tax = 0.1;
B) purchase.Tax = 0.1;
C) dblTax = 0.1;
D) currentSale.dblTax = 0.1;
E) currentSale.ReadOnlyProperty = 0.1;

Answer 1

None of the given options A to E are valid because they all attempt to assign a value to a read-only property or a private variable from outside the class, which is not allowed in object-oriented programming.

Step-by-step explanation:

The question pertains to a property in object-oriented programming. In the given scenario, as the tax property is read-only and dbltax is a private variable, neither of them can be set directly from outside the class that defines them. In a read-only property, the value can typically only be assigned during the initialization of the object or within the class itself, not from an external class such as a click event procedure.

Therefore, options A) currentSale.Tax = 0.1; B) purchase.Tax = 0.1; C) dbltax = 0.1; D) currentSale.dblTax = 0.1; and E) currentSale.ReadOnlyProperty = 0.1 are all invalid, as they attempt to assign a value to a read-only property or a private variable from outside the class.

In the given scenario, the purchase class contains a readonly property named tax associated with the private dbltax variable. The click event procedure instantiates a purchase object and assigns it to the currentSale variable.

Since the property 'tax' is declared as readonly, its value cannot be modified after it is set. Therefore, option A) currentSale.Tax = 0.1; is not valid.

To modify the value of the 'tax' property, we need to access it through the object itself. Hence, the valid statement would be D) currentSale.dblTax = 0.1; as it assigns the value 0.1 to the private variable dbltax.