(* ==============================================================================
 *    File: GradeCalculator2.p
 *  Purpose: Simple program to calculate the percentage and letter grade
 *           with procedures and functions
 *  Author: Jordan Kidney ( kidney@cpsc.ucalgary.ca )
 * Created on: Feb 24, 2006
  ============================================================================== *)
program GradeCalculator2 (input,output);

(*----------------------- readTotalMarks ----------------------------------------
 * Purpose: prompts the user to enter in the total marks for the test. This 
 *          function also does some basic error checking on the number entered.
 * returns: the number entered by the user as a real
 *------------------------------------------------------------------------------ *) 
function readTotalMarks : real;
 begin
   var marks   : real;
   var EndLoop : boolean; (* Used as a flag to end loops for error checking *)
   

   EndLoop := false;      
   repeat
       write('Enter the total number of marks : ');
       readln(marks);
       if (marks <= 0) then
          writeln('Error: The number must be greater then zero.')
       else
          EndLoop := true
     
   until EndLoop = true;

   readTotalMarks := marks;
 end;
(*----------------------- readUsersMark -----------------------------------------
 * Purpose: prompts the user to enter the mark they got for the test. This
 *          function also does some basic error checking on the number entered.
 * Parameters: TotalMarks - the total number of possible marks on the test. This
 *                          value is used for error checking.
 * returns: the number entered by ther use as a real
 * ------------------------------------------------------------------------------ *)
function readUsersMark(TotalMarks : real) :  real;
begin
   var mark    :  real;
   var EndLoop :  boolean; (* Used as a flag to end loops for error checking *)
   
   EndLoop := false;
   repeat
      write('Enter your mark : ');
      readln(mark);
      if ((mark < 0) or (mark > TotalMarks))  then
	  writeln('Error: inncorect input')
      else
	  EndLoop := true

    until EndLoop = true; 

   readusersMark := mark;
end;
(*----------------------- computePercentage ------------------------------------
 *  Purpose: computes the percentage the user got
 *  Parameters: TotalMarks - the total number of possible marks on the test.
 *              Mark       - the mark the user got on the test 
 *  returns: the number entered by ther use as a real
 *----------------------------------------------------------------------------- *)
function computePercentage(TotalMarks , Mark : real ) : real;
 begin
    computePercentage := (Mark * 100.0)/TotalMarks;
 end;
(*----------------------- findLetterGrade -----------------------------------------
 * Purpose: find the letter grade based upon a given percentage value
 * Parameters: percentage - the percentage used to find the letter grade
 * returns: the letter grade as a string
 *------------------------------------------------------------------------------- *)
function findLetterGrade(percentage :  real ) : string;
 begin
    var LetterGrade :  string[3];

    if (Percentage < 39.0) then LetterGrade := 'F'
    else if (Percentage < 44.0) then LetterGrade := 'D-'
    else if (Percentage < 49.0) then LetterGrade := 'D'
    else if (Percentage < 54.0) then LetterGrade := 'D+'
    else if (Percentage < 59.0) then LetterGrade := 'C-'
    else if (Percentage < 64.0) then LetterGrade := 'C'
    else if (Percentage < 69.0) then LetterGrade := 'C+'
    else if (Percentage < 74.0) then LetterGrade := 'B-'
    else if (Percentage < 79.0) then LetterGrade := 'B'
    else if (Percentage < 84.0) then LetterGrade := 'B+'
    else if (Percentage < 89.0) then LetterGrade := 'A-'
    else LetterGrade := 'A';

    findLetterGrade := LetterGrade;
 end;  				    
(* ========================== MAIN ============================================== *)
begin
      var Mark        : real; (* The mark the user got *) 
      var TotalMarks  : real; (* Total number of possible marks *)
      var Percentage  : real; (* Used to store the calculated percentage value *)	
      var LetterGrade : string[3]; (* Used to store the letter cade for the mark *)

      TotalMarks := readTotalMarks;	
      Mark := readUsersMark(TotalMarks);
      
      Percentage  := computePercentage(TotalMarks,Mark);
      LetterGrade := findLetterGrade(Percentage);
      
      (* Write information to the console *)
      writeln('You got ', Percentage:0:2,
	      '% on the test which gives you a letter grade of ',LetterGrade);
end.
(* ============================================================================== *)