Question

I am having trouble understanding how this code is able to use the contents of the header file. Can someone please provide brief comments in the top code to show what is happening?

THE CODE:

#include<bits/stdc++.h>
#include "MyCartesianPoint.h"
#include <math.h>
#include <iostream>

using namespace std;

bool isNumber(string s)
{
   if(!isdigit (s[0]))
   {
       if(s[0] != '-')
       return false;
      
       else if(s.length() == 1)
       return false;
   }
  
   for (int i = 1; i < s.length(); i++)
   if (isdigit(s[i]) == false)
  
   return false;
   return true;

}

int main()
{
   string x, y;
   int X, Y;

CartesianPoint::SetLimit(10);
vector<CartesianPoint> v;
CartesianPoint origin(0,0);
v.push_back(origin);
cout << "You will be travelling from (0, 0) to (10, 10) in as many steps as you like. Enter (10, 10) to end.\n";
  
do
{
   cout << "Move from " << v.back().ToString() << " to where? ";
   CartesianPoint p;
  
       cout << "\nX:";
   while(true)
   {
       cin >> x;
         
       if(isNumber(x))
       {
               try
           {
               X = stoi(x);
                   p.SetX(X);
                   break;
           }
               catch(exception& e)
               {
                   //if there is an exception
                   cout << "* Invalid input. " << e.what() << " ";
               }
           }
         
       else
       cout << "* Invalid input. Please try again and enter a numeric value. ";
   }
  
   cout << "Y:";
     
   while(true)
   {
       cin >> y;
         
       if(isNumber(y))
       {
           try
           {
                   Y = stoi(y);
                   p.SetY(Y);
                   break;
               }
              
               catch(exception& e)
               {
                   // If there is an exception:
                   cout << "* Invalid input. " << e.what() << " ";
               }
           }
          
       else
       cout << "* Invalid input. Please try again and enter a numeric value. ";
   }
  
// Insert into v:
v.push_back(p);
  
}

while(X != 10 || Y != 10);
  
double dist = 0;
cout << "DEBUGGING ONLY:\n";
for(int i = 0; i < v.size() - 1; i++)
{
   double d = v[i].GetDistanceTo(v[i + 1]);
   cout << v[i].ToString() << " -> " << v[i + 1].ToString() << ": " << fixed << setprecision(2) << d << endl;
  
   dist += d;
}
cout << "\nFINAL OUTPUT:\n";
cout << "The total distance between " << v.size() << " points is " << fixed << setprecision(2) << dist << ".";
}

HEADER FILE:

#ifndef MY_CARTESIAN_POINT_H

#define MY_CARTESIAN_POINT_H

#include <iostream>        // cin, cout
#include <sstream>            // stringstream
#include <cmath>           // sqrt()
#include <limits>           // INT_MAX
#include <stdexcept>       // out_of_range

using namespace std;

// class declaration section
class CartesianPoint
{
public:
/* Constructor: Used to initialize objects */
CartesianPoint(int x = 1, int y = 1) { SetPoint(x, y); }
  
/* Accessors: Used to query the state of the object */
   int GetX() const { return myX; }
   int GetY() const { return myY; }
  
// get the distance between this point and a second point
    double GetDistanceTo(CartesianPoint pointTo) const;
    string ToString() const; // convert the obj to a string.  
  
/* Mutators: Used to change the state of the object */
   void SetX(int x) { myX = validateCoordinateValue(x); }
   void SetY(int y) { myY = validateCoordinateValue(y); }
   void SetPoint(int x, int y) { SetX(x); SetY(y); }  
  
/* Static methods:
       - Can be used to access/mutate static data members
       - Can be called without an object
   */
   // get the limit
   static int GetLimit() { return sharedLimit; }
   // set the limit
   static void SetLimit(int limit) { sharedLimit = abs(limit); }

/* Friend Functions: Nonmember functions/methods that are granted the same
        privileges as member methods
*/
// TO-DO: Add ReadCartesianPoint() to the friends list
   
     
private:
// private data members for the dimensions of the point
int myX; // x-axis (horizontal) value
int myY; // y-axis (vertical) value
  
// Static data-member: Shared among all objects of this class.
   static int sharedLimit;
  
// Helper method for validation
int validateCoordinateValue(int value) const;

};

// Class definition section

/** sharedLimit static data-member for CartesianPoint class
*   Used to validate the x and y coordinate values.
*/
int CartesianPoint::sharedLimit = INT_MAX;

/** GetDistanceTo Method for CartesianPoint class
*   Determines the distance between this point and a second point.
*   @param   pointTo: CartesianPoint
*   @return   the distance as a double
*/
double CartesianPoint::GetDistanceTo(CartesianPoint pointTo) const
{
int xDelta = pointTo.myX - myX; // difference between x values
int yDelta = pointTo.myY - myY; // difference between y values
// return the formula (based on Pythagorean theorem)
   return sqrt((xDelta * xDelta) + (yDelta * yDelta));
}

/** ToString Method for CartesianPoint class
*   Converts the obj to a string.
*   @return   the obj state as a string
*/
string CartesianPoint::ToString() const
{
   // declare a stringstream object
   stringstream strOut;
   // build the string
   strOut << "(" << myX << ", " << myY << ")";
   // return the string
   return strOut.str();
}

/** validateCoordinateValue Method for CartesianPoint class
*   Determines if the parameter is valid for a coordinate value.
*   @param   value (int)
*   @return   the parameter if valid
*   @throws an out_of_range exception if not in range
*/

int CartesianPoint::validateCoordinateValue(int value) const
{
   // if the parameter is within the limits
   if((value < -sharedLimit || value > sharedLimit))
   {
       // throw an exception
       throw out_of_range( "Parameter (" + to_string(value) + ") must be between "
           + to_string(-sharedLimit) + " and " + to_string(sharedLimit) + ".");
   }
  
   return value;
}

#endif

Answer 1

I have tried to explain how header file has been used in the main program through comments.I have highlighted those in bold .Also go through the mehod i have mentioned in code for better understanding

--------------------------------

main.cpp

#include<bits/stdc++.h>
#include "MyCartesianPoint.h"
#include <math.h>
#include <iostream>

using namespace std;

bool isNumber(string s)
{
if(!isdigit (s[0]))
{
if(s[0] != '-')
return false;
else if(s.length() == 1)
return false;
}
for (int i = 1; i < s.length(); i++)
if (isdigit(s[i]) == false)
return false;
return true;

}

int main()
{
string x, y;
int X, Y;
//This is defined in header file.This set the limit that the point
//coordinates must be between the limit ie 10 here.Used in cordinate class for validation of point
//coodinates.
CartesianPoint::SetLimit(10);
//create a vector of CartesianPoint class defined in header file.
vector<CartesianPoint> v;
CartesianPoint origin(0,0);//Create an object of CartesianPoint class.Initialization is in header file as CartesianPoint(int x = 1, int y = 1)
v.push_back(origin);
cout << "You will be travelling from (0, 0) to (10, 10) in as many steps as you like. Enter (10, 10) to end.\n";

do
{
cout << "Move from " << v.back().ToString() << " to where? ";
CartesianPoint p;

cout << "\nX:";
while(true)
{
cin >> x;

if(isNumber(x))
{
try
{
X = stoi(x);
p.SetX(X);
break;
}
catch(exception& e)
{
//if there is an exception
cout << "* Invalid input. " << e.what() << " ";
}
}

else
cout << "* Invalid input. Please try again and enter a numeric value. ";
}

cout << "Y:";

while(true)
{
cin >> y;

if(isNumber(y))
{
try
{
Y = stoi(y);
p.SetY(Y);
break;
}

catch(exception& e)
{
// If there is an exception:
cout << "* Invalid input. " << e.what() << " ";
}
}

else
cout << "* Invalid input. Please try again and enter a numeric value. ";
}

// Insert into v:
v.push_back(p);

}

while(X != 10 || Y != 10);

double dist = 0;
cout << "DEBUGGING ONLY:\n";
for(int i = 0; i < v.size() - 1; i++)
{
double d = v[i].GetDistanceTo(v[i + 1]);//this method is defined in header file as double CartesianPoint::GetDistanceTo(CartesianPoint pointTo) const
//and calulates the distance of an point form another
cout << v[i].ToString() << " -> " << v[i + 1].ToString() << ": " << fixed << setprecision(2) << d << endl;

dist += d;
}
cout << "\nFINAL OUTPUT:\n";
cout << "The total distance between " << v.size() << " points is " << fixed << setprecision(2) << dist << ".";
}

---------------------------------

MyCartesianPoint.h //////////This is same as earlier

#ifndef MY_CARTESIAN_POINT_H

#define MY_CARTESIAN_POINT_H

#include <iostream> // cin, cout
#include <sstream> // stringstream
#include <cmath> // sqrt()
#include <limits> // INT_MAX
#include <stdexcept> // out_of_range

using namespace std;

// class declaration section
class CartesianPoint
{
public:
/* Constructor: Used to initialize objects */
CartesianPoint(int x = 1, int y = 1)
{
SetPoint(x, y);
}

/* Accessors: Used to query the state of the object */
int GetX() const
{
return myX;
}
int GetY() const
{
return myY;
}

// get the distance between this point and a second point
double GetDistanceTo(CartesianPoint pointTo) const;
string ToString() const; // convert the obj to a string.

/* Mutators: Used to change the state of the object */
void SetX(int x)
{
myX = validateCoordinateValue(x);
}
void SetY(int y)
{
myY = validateCoordinateValue(y);
}
void SetPoint(int x, int y)
{
SetX(x);
SetY(y);
}

/* Static methods:
- Can be used to access/mutate static data members
- Can be called without an object
*/
// get the limit
static int GetLimit()
{
return sharedLimit;
}
// set the limit
static void SetLimit(int limit)
{
sharedLimit = abs(limit);
}

/* Friend Functions: Nonmember functions/methods that are granted the same
privileges as member methods
*/
// TO-DO: Add ReadCartesianPoint() to the friends list

private:
// private data members for the dimensions of the point
int myX; // x-axis (horizontal) value
int myY; // y-axis (vertical) value

// Static data-member: Shared among all objects of this class.
static int sharedLimit;

// Helper method for validation
int validateCoordinateValue(int value) const;

};

// Class definition section

/** sharedLimit static data-member for CartesianPoint class
* Used to validate the x and y coordinate values.
*/
int CartesianPoint::sharedLimit = INT_MAX;

/** GetDistanceTo Method for CartesianPoint class
* Determines the distance between this point and a second point.
* @param pointTo: CartesianPoint
* @return the distance as a double
*/
double CartesianPoint::GetDistanceTo(CartesianPoint pointTo) const
{
int xDelta = pointTo.myX - myX; // difference between x values
int yDelta = pointTo.myY - myY; // difference between y values
// return the formula (based on Pythagorean theorem)
return sqrt((xDelta * xDelta) + (yDelta * yDelta));
}

/** ToString Method for CartesianPoint class
* Converts the obj to a string.
* @return the obj state as a string
*/
string CartesianPoint::ToString() const
{
// declare a stringstream object
stringstream strOut;
// build the string
strOut << "(" << myX << ", " << myY << ")";
// return the string
return strOut.str();
}

/** validateCoordinateValue Method for CartesianPoint class
* Determines if the parameter is valid for a coordinate value.
* @param value (int)
* @return the parameter if valid
* @throws an out_of_range exception if not in range
*/

int CartesianPoint::validateCoordinateValue(int value) const
{
// if the parameter is within the limits
if((value < -sharedLimit || value > sharedLimit))
{
// throw an exception
throw out_of_range( "Parameter (" + to_string(value) + ") must be between "
+ to_string(-sharedLimit) + " and " + to_string(sharedLimit) + ".");
}

return value;
}

#endif