#include<iostream>
#include<string>

/*		CSC15 Final Exam Study Guide, with sample solutions


The final exam will be cumulative.  All topics covered on the Midterm will
also be covered (refer to the midterm study guide on the web page).  
Pay particular attention to the definition and use of classes and objects.

You will be asked to write a number of small functions that require the use
of loops, arrays, and strings.  These functions will be mostly similar to 
examples we've done in class.

You will be asked to write a class and demonstrate the creation of objects, as
on the midterm.  The class must be written from scratch.

There will be one or two questions that are intended to be difficult.  


What to study:

Class notes
Sample programs I've written, some of which are on the web page.
Midterm and quizzes
Past labs and assignments
Portions of the text that parallel the lectures
Class notes


REVIEW SESSION SUNDAY 5/13 at 2pm (in regular classroom).




Sample Problems:


1.  Write a function that takes an array of integers and multiply each element
of the array by 2.  For example, {1,3,5} should become {2,6,10}.
*/

void doublearray(int A[], int size)
{
   int i; // loop counter
   i = 0;
   while (i<size)
       {  A[i] = A[i] * 2;
          i++;
       }
   // for loop: for(i=0;i<size;i++) { A[i] = A[i] * 2; }
} // double


/*
2.  Write a function that takes an array of integers and return a string with
every character in the string created from converting the corresponding integer
in the array into a ascii character.  For example, with {65,66,67} your
function should return "ABC".
*/

string makestring(int A[], int size)
{
  string answer = "";   // string to be constructed char by char
  int i; // loop counter
  for(i=0;i<size;i++)
      { answer = answer + (char) A[i];  // add char to end of string
      } // for
  return answer;
} //makestring

/*
3.  A string is called a "palindrome" if it reads the same forwards and
    backwards, for example, "noon", "bob", "abba" are all palindromes.
    Write a function that returns true if a string (parameter) is a palindrome,
    and false otherwise.  
*/

bool palindrome(string s)
{
   bool answer = true;
   int i = 0;
   while (i<(s.size()/2) && answer)
       {
	   if (s[i] != s[s.size()-i-1]) answer = false; 
	   i++;
       } // while
   return answer;
} // palindrome

   // second version: define function to reverse a string first
string revstring(string a)
    {  string answer = "";
       int i;
       for(i=0;i<a.size();i++)
	   { 
	       answer = a[i] + answer;
	   }
       return answer;
    } // revstring

// second version of palindrome function:
bool palindrome2(string s)
    {
	return s == revstring(s);
    }


/*
4.  A line can be represented by a "slope" and a "y-intercept".  For example,
    in y=2x+4, 4 is the y intercept and 2 is the slope.  The general equation
    is y = (slope * x) + yintercept.  

    Write a class "line" representing a line based on these two attributes.  
    It should contain in the private section double values "slope" and
    "yintercept".  Use double instead of int everywhere to avoid confusion.
    Please be careful: the class contains the slope and yintercept, NOT x and
    y.

    In the public section, write:

      both a regular constructor and an alternate (empty) constructor

      a function yplot that returns the y coordinate of a point on the 
      line given its x coordinate.  For example, for a line with slope = 2,
      and yintercept = 4, calling yplot(3) should return 10 
      (because y=2*x+4 and so 2*3+4 =10).

      a function xplot that similarly returns the x coordinate of a point
      given the y coordinate.  Remember your high school algebra?  I'm
      sure you do, but just in case: x = (y-yintercept)/slope. If the
      slope is zero, cout a message and return + or - 1 billion as the 
      default value.
   
      a function online that takes two parameters x,y representing a
      point as arguments, and returns true if the point is on the line that
      the object is representing, and false otherwise.  (the math is
      easy: just use either of the above functions to see if the coordinates
      are consistent).
*/
class line
{
    private:
       double slope;
       double yintercept;

    public:

    line(double s, double y)   // constructor
    { slope = s;  yintercept = y; }
    
    line() {} // alternate constructor

    double yplot(double x)
    {  return (x*slope) + yintercept; }

    double xplot(double y)
    {  return (y-yintercept)/slope; }

    bool online(double x, double y)
    { return y == yplot(x); }

}; // end class line

//   Write a main function to demonstrate


int main()
{
    int A[4] = {33,34,35,36};
    string s = "noon";
    line l;  // will be initialized later
    double xcoord, ycoord;

    doublearray(A,4);
    cout << makestring(A,4) << endl;
    cout << (palindrome(s) && palindrome2(s)) << endl;  // prints 1 for true

    l = line(1.5,2.0);
    ycoord = l.yplot(3.0);
    cout << (3.0 == l.xplot(ycoord)) << endl;  // prints 1 for true;
    cout << l.online(4.5,3.6) << endl;       // prints 0 for false;
    
  return 0;
}

/* output of this program:

BDFH
1
1
0

*/