CSE 130   Spring 2010

                                 Lab 10


 DO NOT SUBMIT THIS. THIS IS FOR YOUR PRACTICE ONLY.

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 1. Structures

 -    This exercise is about structures and how to use  them  in  func-
      tions. Study the global definition structure `amnt' given to you.
      It has been renamed as amount using typdef. See that statement as
      well.  This structure has been declared above main, so it is glo-
      bal to all functions (available everywhere).

 -    Copy lab10.c from this page. Cut and paste it in your  pico  win-
      dow.

// lab10.c
// CSE 130 Spring 2009. Lab 10, April 14, 2010.
// Sample program for studying structures and functions

// Global declaration for type amount

   #include <stdio.h>

   struct amnt   // struct amnt will be redefined as amount
     { int dollars;
       int cents; };

   typedef struct amnt amount;  // This defines amount.

// amount is another name for type struct amnt.
// Now type amount is available to all functions.

// Code for function add

// Code for function rownd (round is in Math library)
// So we use a different name.

// Code for allDollars

   int main (void)
     {
      //  Declare structure variables a, b of type amount.
      //  Additional Variable declarations .

      printf("Type in Amount-1 in dollars and cents.\n");
      scanf ("%d%d", &a.dollars, &a.cents );

      printf("Type in Amount-2 as dollars and cents.\n");
      scanf ("%d%d", &b.dollars, &b.cents );

      // Call functions as required and print results.

      return 0;
    }


 -    After pasting it in pico window, save it as lab10.c.  Do not com-
      pile  right  away. Insert declaration for a, b.  Both are of type
      amount. Now compile  and  execute.   The  program  will  ask  for
      amounts  a  and  b.   Just  type in some values. Program will end
      without doing anything, as there are no additional statements.

 2. Function add

 a.   Write code for function add that takes two arguments x, y of type
      amount. It adds them and returns the result as a structure.  This
      code should be in its place indicated by the comment above
      main( ).

 b.   First write the header for add. What is its type?   What  is  the
      type of its arguments?

 c    You will need a local variable c of type  amount.   Declare  that
      inside  the  body of `add'.  Now calculate c.dollars and c.cents.
      Handle the case if c.cents exceed 99.

 d.   Return c at the end. Enclose the body with { }.

 e.   In the main program, insert a call to function  add.   Parameters
      are a, b. Get the result back in another variable of type amount.
      You may use c again. Declare c of type amount.

 f.   Insert a print statement for printing c.dollars and c.cents.  See
      scanf statement for some hints.

 g.   Save, compile and execute. Does it print addition of two amounts?
      Test  with  a = 20 87 and b = 1 45 Here answer will be 22 dollars
      and 32 cents.

 3. The function rownd (see the name)

 h    This function rounds a given amount and returns the rounded value
      as  an  integer  dollars.  It has one parameter x of type amount.
      This code should be in its place indicated for round by the  com-
      ment above main( ).

 i.   First write the header for round. What is its type?  What is  the
      type of its argument?

 j    You will need a local variable  i  of  type  int.   Declare  that
      inside  the body of `round'.  Calculate i as follows.
      if x.cents < 50 then i = x.dollars else i = x.dollars + 1;

 k.   Return i at the end. Close the body.

 l.   In the main program, insert two calls to function rownd.  One for
      amount  a  and one for amount b. To save typing extra statements,
      have these calls in the printf statement itself. For example,
      printf("\nRounded amount a is: %d", \n rownd(a));
      Insert one for b as well.

 m.   Save, compile and execute.  Does  it  print  rounded  values  for
      amounts  a  and b?  Test with a = 20 87 and b = 1 45 Here rounded
      amount a is 21 and that for b is 1.

 4. Function allDollars

 n    This function converts the given amount to  a  decimal  value  in
      dollars  and returns it. Type of returned value is float.  It has
      one parameter x of type amount.  This code should be in its place
      indicated for allDollars by the comment above main().

 o.   First write the header for allDollars. What is its type?  What is
      the type of its argument?

 p    You will need a local variable f of  type  float.   Declare  that
      inside  the  body  of  `allDollars'  Calculate f as follows.  f =
      (float)x.dollars + (float)x.cents/100.0;

 q.   Return f at the end. Close the body.  See  if  you  can  do  this
      without  declaring  variable  f.  Just use the expression in your
      return statement.

 r.   In the main program, insert two calls to  function  `allDollars'.
      One  for  amount  a  and  one  for amount b. To save typing extra
      statements, have these calls in the printf statement itself.  For
      example,
      printf("\nAmount in dollars for a is: %f", \n allDollars(a));
      Insert one for b as well.

 m.   Save, compile and execute.  Does  it  print  decimal  values  for
      amounts  a and b?  Test with a = 20 87 and b = 01 45 Here decimal
      amount for a is 20.87 and that for b is 1.45.