CSE399: Homework 1

1. Hello World

    10 points
    Estimated time: 5 minutes
   In a file called hello.c, write a program
   which prints "Hello World" as output.  Compile
   the program so that the resulting binary is
   called hello (using -o hello), and run it
   (./hello).
   
   [Yes, the code for this was given in lecture-
    this problem is just to get you started]
   
   
    Factorial
    40 points  (Step 0: 0 points, Step 1: 20 points, Step 2: 20 points)
    Estimated time: 15 minutes
   
     Download the files: factmain.c and fact.h 
   
   fact.h provides the following prototype for factorial:
   
     int factorial (int x);
   
   
   As you may recall, factorial(0) should return 1,
   and factorial(x) should return x * factorial(x-1)
   for any other positive x.  Your factorial function
   may exhibit any behavior on negative inputs.
   You may use either recursive or iteration.
   
   
    Step 0:  Try compiling factmain.c (just do gcc factmain.c). 
   You should receive an error message from the linker that
   looks like this:
      /tmp/ccIFxXDl.o: In function `main':
     factmain.c:(.text+0x19): undefined reference to `factorial'
     collect2: ld returned 1 exit status
   
   This error results from the fact that there is no input
   procividing a definition of factorial.  
   Now recall that compilation can be stopped at simply an object
   file (gcc -c factmain.c).  This command should complete
   with no errors, and the object file factmain.o should
   now exist. 
   
    Step 1:   Create a file called fact.c which 
   #include's fact.h, and defines the factioral function
   described above.   Once you have a working implementation
   compile it to an object file
   (gcc -std=c99 -pedantic -Wall -Werror -c fact.c).
   Now link fact.o and factmain.o together to make
   the binary fact
   (gcc -o fact factmain.o fact.o).
   Try running the program (./fact) to test your code.
   
    Step 2: The above description of factorial specified
   that your code does not need to deal with negative
   inputs, however, factmain.c does not check for this
   condition.  Edit factmain.c so that if
   the user inputs a negative number, the program
   prints the error message "Negative numbers are not allowed!"
   instead of calling factorial.
   Recompile and test your code.  Note that
   you do not need to recompile fact.c to fact.o since
   that has no changed.  Also note, that you can
   just do this in one command:
   (gcc -o fact -std=c99 -pedantic -Wall -Werror fact.o factmain.c)
   gcc is smart enough to know what to do with each input file.
   
   
    Some array basics
     40 points  (4 functions, 10 points each)
     Estimated time: 15 minutes
   
   
   This problem will cover the aspects of arrays that
   look like Java arrays.  For this problem you will
   be editing the file arrays.c.
   You must fill in the code for the following 4 functions:
   
    
    sumArray: returns the sum of the elements of the array
    
    findMax: returns the largest element of the array
    
    printAllElements: prints out the contents of the
                          array in the following format:
        array[0] = 10
        array[1] = 15
        array[2] = 7
   
    
    sortArray: sorts the array into ascending order.
                    You may use any sorting algorithm you want.
                    As efficiency does not matter, bubble sort
                   is likely the easiest.
   
   Recall that unlike java, arrays do not have a length
   field, so the length of the array is passed as a separate
   argument.
   
   
   
    Feedback
      10 points
      Estimated time: 5 minutes
   
   
   In a text file called feedback.txt, briefly let
   me know what you thought of this homework.  Was
   it too hard or too easy?  Did you feel like
   it was useful in getting you acquainted
   with the basics of C?
   
   

Submitting your assignment!

 CSE399: Homework1 Submission

  zip adhilton.hwk1.zip *.c *.h hello feedback.txt

 mutt -a adhilton.hwk1.zip -s"CSE399: Homework1 Submission" adhilton@cis.upenn.edu < /dev/null