CSE 130         Fall 2009

                                 Lab 3


 NOTE: It is very important for this course that  you  have  an  active
 sparky  account  for  completing  assignments.  If you don't have one,
 visit the SINC site in the  main  library  building  and  speak  to  a
 representative to resolve this as soon as possible.

 TA will help you with the following exercise.

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

 1. lab2.c Revisited


 a.   During our second exercise, we studied lab2.c program that prints
      the  numbers  from  1  to  10  (on  one  line).  The while (test-
      condition) {.. body ..} statement causes the {.. body ..}  to  be
      repeated  as  long  as the (condition) is true. The <= is how one
      types "less than or equals".

 b.   The int i=1; statement has been  changed  to  two  statements  as
      explained later.

// This is lab3.c
// A different version of previous program.
// Sample program to print: 1 2 3 4 5 6 7 8 9 10.
// if user types a starting value = 1.
// Example for class CSE130.
// We print i using printf function.
// Use of %d means i will be printed as a decimal integer.
// There is a space before % character.

   #include <stdio.h>
   int main (void)
     {  int i;             // Indentation is important.

        printf("Type in starting value for i: \n");
        scanf("%d", &i);
        while (i <= 100)
           { printf(" %d", i);
             i=i+1;
           }
        printf(".\n");
        return 0;
     }


 c.   After sign-on, change your working directory to cse130.  The com-
      mand is: cd cse130

 d.   Open the editor window for pico by typing pico.   Cut  and  paste
      lab3.c  to  your  pico  window.  Save as lab3.c (ctrl-o) and exit
      (ctrl-x).

 e.   Note that here we just have int i; as a  declaration  for  i.  We
      read starting value for i from the user.

 f.   TA will discuss indentation and explain why  is  that  important.
      All  program must be properly indented.  Some points are reserved
      for that.

 g.   Compile  your  program  and  execute.  (gcc  lab3.c  followed  by
      ./a.out) Try i = 1

 h.   It should output 1 2 3 4 5 6 7 8 9 10 ...... up to 100.

 2. Modification - I

 i.   For this program the increment in i is always 1.  This is because
      we have i = i+1; in our while loop.

 j.   Replace that statement with i = i+j; Make sure that j is declared
      as in integer. Either insert int j, or have int i, j;

 k.   Also do not forget to initialize j to whatever increment that you
      want.  Let us give j a value of 4. This must be done before while
      loop. A good place would be after the scan statement  that  reads
      i.

 l.   Save your program, compile and execute. Try i = 7.  See  what  it
      prints.

 3. Modification - II

 m.   Instead of using a fixed value for j, we can ask user for a value
      for j as well. This is our increment in i.

 n.   Delete j = 4; Insert a print statement that should say Type in  a
      value for increment j. Do not forget to add \n.

 o.   Follow this up with a scanf statement           scanf("%d", &j);

 p.   Save your program. Compile and execute. Try different values of i
      and j for every execution. Try i = 8, j = 9.

 4. Modification - III

 q.   What if we want to add values of i that are  getting  printed  by
      our while loop?

 r.   So we declare a variable called total. What should be  its  type?
      Initialize it to 0.

 s.   Inside the loop, just after we print i, accumulate total by doing
      total = total + i;

 t.   Print total outside the loop, but after the dot (`.')   has  been
      printed. Use a printf statement. Follow the format Total = ____

 u.   Save your program, compile and execute. Try i = 1, j = 10.  Total
      should be 460

 5. Modification - IV

 v.   If you run out of time try this later.

 w.   Now after you print the period ("."), calculate square of  i  and
      cub of i. You need to declare these two variables.

 x.   Before return 0; statement insert two statements.
      i_sq = i * i;  and i_cube = i_sq * i;

 y.   Print i_sq and i_cube using a printf statement.

 z.   Format is:       i_sq =         , i_cube =
      Do not forget the \n at the end of printf statement.