Defining header files in C++ - c++

Question

To start off with, I'll mention I come mainly from a Java background. I do have exposure with C and understand most concepts behind C++. I'm trying to help myself learn more about the language and can't seem to figure out headers. I understand why to use them in addition to cpp files and all of that. My problem is trying to actually manage working with them. For example, defining a Vector3 header with private float variables and then overload operating. My problem comes in when I attempt to define the constructor and methods in the cpp file. I can't seem to figure out how to get access to the private variables without specifically defining the functions and the constructor in the header, which more or less leads me to believe I don't need both a header and cpp file in this instance.
Here's how I've defined the header file currently (which works, but isn't undefined as it should be):
#pragma once
#ifndef __Vector_3_H__
#define __Vector_3_H__
namespace VectorMath {
class Vector3 {
public:
Vector3(float x, float y, float z) {
this->x = x;
this->y = y;
this->z = z;
}
Vector3 operator+(Vector3 vector) {
return Vector3(x + vector.x, y + vector.y, z + vector.z);
}
Vector3 operator-(Vector3 vector) {
return Vector3(x - vector.x, y - vector.y, z - vector.z);
}
Vector3 operator*(Vector3 vector) {
return Vector3(x * vector.x, y * vector.y, z * vector.z);
}
Vector3 operator/(Vector3 vector) {
return Vector3(x / vector.x, y / vector.y, z / vector.z);
}
float getX() {
return x;
}
float getY() {
return y;
}
float getZ() {
return z;
}
private:
float x;
float y;
float z;
};
}
#endif

Answer 1

It needs to look more like this instead:
Vector_3.h:
#ifndef Vector_3_H
#define Vector_3_H
#pragma once
namespace VectorMath {
class Vector3 {
public:
Vector3(float x, float y, float z);
Vector3 operator+(Vector3 vector);
Vector3 operator-(Vector3 vector);
Vector3 operator*(Vector3 vector);
Vector3 operator/(Vector3 vector);
float getX();
float getY();
float getZ();
private:
float x;
float y;
float z;
};
}
#endif
Vector_3.cpp:
#include "Vector_3.h"
namespace VectorMath {
Vector3::Vector3(float x, float y, float z) {
this->x = x;
this->y = y;
this->z = z;
}
Vector3 Vector3::operator+(Vector3 vector) {
return Vector3(x + vector.x, y + vector.y, z + vector.z);
}
Vector3 Vector3::operator-(Vector3 vector) {
return Vector3(x - vector.x, y - vector.y, z - vector.z);
}
Vector3 Vector3::operator*(Vector3 vector) {
return Vector3(x * vector.x, y * vector.y, z * vector.z);
}
Vector3 Vector3::operator/(Vector3 vector) {
return Vector3(x / vector.x, y / vector.y, z / vector.z);
}
float Vector3::getX() {
return x;
}
float Vector3::getY() {
return y;
}
float Vector3::getZ() {
return z;
}
}

Answer 2

If you want to use a cpp file for your constructor you should write
// File Vector3.cpp
#include "Vector3.h"
namespace VectorMath {
Vector3::Vector3 (float x, float y, float z)
{
this->x=x;
//...
}
The addition should be implemented as follows if you keep it in the same namespace
Vector3 Vector3::operator+(const Vector3& v)
{
return Vector3 (x+v.x,y+v.y,z+v.z);
}
}

Answer 3

If you want to move the implementations of member functions away from the header file, you still need to declare them in the definition of the class. For example:
// Vector1.h
#pragma once
#ifndef VectorMath_Vector1_H
#define VectorMath_Vector1_H
namespace VectorMath {
class Vector1 {
public: // Methods:
// This is a definition for a default constructor:
Vector1() noexcept : m_x(0) {}
// This is a declaration for another constructor:
Vector1(float x) noexcept;
// This is a declaration of a member function:
Vector1 operator+(Vector1 const & rhs) const noexcept;
private: // Fields:
float m_x;
}; // class Vector1
} // namespace VectorMath {
#endif // VectorMath_Vector1_H
// Vector1.cpp
#include "Vector1.h"
namespace VectorMath {
// Definition of the other constructor:
Vector1::Vector1(float x) noexcept
: m_x(x)
{}
// Definition of the binary + operator:
Vector1 Vector1::operator+(Vector1 const & rhs) const noexcept
{ return m_x + rhs.m_x; }
} // namespace VectorMath {