C++ tutorial - a 3D vector & transform library

If the first program that C++ coders write is “Hello World”, then a definition of a 3D vector class is probably the second.

Let’s have a go:

#include <iostream>	// For console output functionality

using namespace std;	// Avoids having to use std:: scoping prefix

class Vector
{
public:
	double x,y,z;	// Representation

	Vector(double a,double b,double c):x(a),y(b),z(c) { }	// Constructor

	friend ostream& operator<<(ostream& os,const Vector& v)	// Non-member, thus must be friend, but defined inline
	{ return os<<'('<<v.x<<','<<v.y<<','<<v.z<<')'; }	// Output, e.g. (1,2,3)
};

int main()	// The program
{	Vector v(1,2,3);	// A test vector

    cout << "v="<<v<<"\n";	// Output it
}

When this is run it produces the following output:

v=(1,2,3)

There’s not much we can do with this vector. We can read and write to the individual elements (x,y,z), but addition is labourious, e.g.

Vector u(-1,-3,-5);

cout<<"u="<<u<<"\n";

Vector s=Vector(u.x+v.x,u.y+v.y,u.z+v.z);	// Sum of two vectors

cout<<"u+v="<<s<<"\n";

When this is run it adds the following output:

u=(-1,-3,-5)
u+v=(0,-1,-2)