How to Setup and Create a Simple Triangle Header File using C++

How to Setup and Create a Simple Triangle Header File using C++ 

1.  Click here for the source file. First, set up the Driver, here a file called triangle_driver.cpp as follows:

//driver file ...it calls the class #include <iostream>    //usually std lib headers in other directories    #include "triangle.h"  //local header using namespace std; int main() {        triangle t1,t2, t3[10];  //just like declaring                                 //a variable                                 //t1,t2, t3[10] are objects and not used        triangle t4(5, 6);       //the numbers stand for base and                                 //height                                          //t3 sets up an array of 10 objects        cout <<"Area of triangle t4 equals "<< t4.area()<<endl;        t1.setBase(3);  //can set values of variables using methods        t1.setHeight(4);        cout<<"Area of triangle t1 equals " << t1.area()<<endl;        t3[0].setBase(5);        t3[0].setHeight(6);        cout<<"Area of triangle t3[0] equals " << t3[0].area()<<endl;        system("pause");        return 0; }

2.  Next set up the header file, here named triangle.h

//write the prototypes/declare data for the class //header file class triangle {        //if you don't say public or private, by        //default it is all private, can mix public/private        //no order public:    //user accessed data, functions            //data has state, functions have behavior            //functions in classes are called methods            //just like prototypes             triangle(); //creates triangle objects                         //constructor...never have return types                         //if no parameters...it is called                         //the default constructor                triangle(double, double); //not a default constructor               //constructor allows you to set base and height                void setBase(double);                void setHeight(double);                double area(); private:       //declaring variables...never make                //variables something the user can declare                //it gives him too much power...this is dangerous                double base, height; //sort of global variable                                      //in the implementation //protected:  //usually use in cases of inheritance };

3.  Finally setup the implementation file, here named triangle.cpp

//implementation...write the functions #include <iostream> #include "triangle.h" using namespace std; //syntax: return type if there is one, write the class you are in :: //scope resolution operator, then the name of the function triangle::triangle() //creates triangle objects {//default constructor    base=0;  //typically in default constructor    height=0; //initialize your variables } triangle::triangle(double b, double h) //not a default constructor {//never in your parameter use the variable names given in the header        //or they will become local to the function        base=b;        height=h; } void triangle::setBase(double b) {        base=b; } void triangle::setHeight(double h) {        height=h; } double triangle::area() {// the 1./ required to create a decimal answer or truncation occurs    return (1./2)*base*height; }