Final Version, Oct 17, 1996

READ THE WHOLE FILE AND DO SO CAREFULLY.

DO NOT TURN THIS IN WITH THE turnin PROGRAM BEFORE
     8 AM Tuesday, OCTOBER 15. If you finish before then, just
     wait a while before turning it in. Also, check for
     changes before turning it in.

CSE 9A  UCSD Fall, 1996
Assignment 3

Due dates for Assignment 3:

>>You must turn it in with the turnin program
  from your account for this class by midnight
  at the end of the day Monday Oct 21. (If you
  miss that deadline, you can turn it in up to 
  24 hours late, but with a penalty.)

>>You must complete an interview for assignment 3
  by the end of the day Monday October 28.
  Note that there is no grace period on the
  interview deadline. 


Reading: Chapters 3 and Section 4.1 of Chapter 4
         all in the Savitch text

Programming: 
In this exercise you will start with a partially
written program and fill in the missing code.
In most cases what is missing are function definitions.
The program with the blanks to fill in 
is in the file hw03.template. You must fill in
some missing code in the main part of the program
and you must give three function definitions.

The completed  program will ask the user if he/she
wants to convert from miles to kilometers or
from kilometers to miles. 
The user responds with the number 1 for
the first case and the number 2 for the second case.
If the user responds with any other number, he/she is
asked the question again, and again until
an appropriate response is made.
The program will then ask for the appropriate
input and compute the appropriate answer.
The program then repeats this action again and
again until the user says to quit.
More specifically, after doing one calculation,
the program asks:
Do you want to do it again? (yes/no).
The user responds with "yes" or "no", but
the program reads only the first letter 'y' or
'n'. (Actually any letter other than 'y' is
interpreted as "no"). Upper or lowercase letters
can be used.

To see what the dialogue should be like you can
run hw03.o which contains the compiled object
code from a solution to this assignment.

Details:
>You do not need to define any functions besides those
whose prototypes are given in hw03.template.

>Be sure to place all function definitions after
main and to leave the function prototypes before
main.

>The function new_line(), whose prototype is
given below, takes zero arguments.
This function will disregard all the input remaining on
a line so that the next time there is a cin, the input
will be taken from the next line. The definition of
new_line is given in hw03.template. You do not
need to understand the definition. You only need
to know how to use the function new_line.

void new_line();

//Discards all the input remaining on the current input line.
>The function from_miles_to_kilometers, whose
prototype is given below, takes no arguments
and returns one of the two letters, uppercase 'M' or uppercase 'K'.
This function is unlike any in the text book in that it
gets it's information by carrying on a dialogue
with the user, rather than having any arguments.
Run the sample object code to see what this dialogue
should be. In particular notice that the user is asked
to input the number 1 or 2, not the letters 'M' or
'K'. Also note that if the user types in some other
number, then they are asked again to enter a number.
THIS FUNCTION MUST USE A LOCAL VARIABLE NAMED ans TO
HOLD THE NUMBER TYPED IN BY THE USER. SO ans WILL BE OF 
TYPE int. (Note that main also has a variable named ans, 
but the one in main is of type char.)

char from_miles_or_kilometers();
//Returns 'M' if the user wants to convert from miles to kilometers.
//Returns 'K' if the user wants to convert from kilometers to miles.
//Gets the answer by asking the user.
//Keeps asking the user until it gets an appropriate answer.


>It is good programming practice check the user's input.
In the function from_miles_or_kilometers the user is asked
to enter 1 or 2. If the user enters any other number, the
user is asked again. This is good and should normally be done
whenever input is accepted from the user.  But, for this assignment,
you only need to do this sort of checking in the
from_miles_or_kilometers function.

October 17, 1996