Question

I have a class Sphere that inherits from class Shape (for a homework project):

Within Shape I have three constructors. The declarations from Shape.h are as follows:

Shape();
Shape(Vector);
Shape(Vector, float[]);

Within Sphere my constructors inherit from these constructors. The declarations in my Sphere.h file are as follows:

Sphere(): Shape() {}//line 17
Sphere(Vector, float): Shape(Vector) {}//line 18
Sphere(Vector, float, float[]): Shape(Vector, float[]) {}//line 19

My syntax here is based largely on looking at templates. While my first language was C++, I was unfortunately taught other concepts, like inheritance, only in Java.

Anyway, I have the following error messages upon `make’:

Sphere.h: In constructor ‘Sphere::Sphere(Vector, float)’:
Sphere.h:18: error: expected primary-expression before ‘)’ token
Sphere.h: In constructor ‘Sphere::Sphere(Vector, float, float*)’:
Sphere.h:19: error: expected primary-expression before ‘,’ token
Sphere.h:19: error: expected primary-expression before ‘float’

Can you help me understand these messages and what might be causing them? I first tried letting them be expressed in the typical way, i.e., instead of

Sphere(): Shape();

and then describing the constructor itself in the .cc file, I did as I had seen done in some online tutorials, without really understanding why:

Sphere(): Shape() {}

This didn’t change anything, the problem remained. Thanks for your help!

Answer 1

You need to specify names, not just types, for the parameters, and pass the names, not the types. For example:

Sphere(Vector a, float b, float[] c): Shape(a, c) {}