CSE399 - C

1
CSE399 - C

• January 16th, 2008
• Policies/Hello World

2
Course Info

• Lecturer Drew Hilton (adhilton_at_cis)
• TA TBA
• Lectures W, noon Town 321
• Office hours TBA
• Webpage
• www.seas.upenn.edu/adhilton/cse399

3
Overview

• C/C
• Somewhat flexible on topics
• Assuming you are eager to learn this
• Last semesters grades
• A 68
• B 29
• C-F 3

4
Textbook

• No required textbook
• Google
• man pages
• 2006s book
• C for Java Programmers
• By Mark A. Weiss

5
Grading

• Homeworks 30
• Project 40
• Exam 20
• 3/4 term- later than a midterm, but not a final
• Class attendance/participation 10
• I reserve the right to include in-class quizzes
  under this category if I feel it is needed

6
Homeworks

• 1-2 weeks each
• Equally weighted
• Partner optional
• Due at start of class
• 5 grace days, then 20 pts/day
• Grading will be done on eniac-l

7
Project

• Large program
• 1-3 people (pairs encouraged)
• Due at end of semester
• Propose topic before Spring Break
• Last years projects
• Games Tetris, Connect 4, etc
• Financial Modeling
• Command shell with meta data in a DB

8
Cheating Policy

• If I were watching, would you do it?
• Working in pairs OK (encouraged!)
• Both partners must participate/learn
• Pair programming
• Separate code, debugging help etc
• Document who/how in comments
• Only your partner should see your code
• When in doubt ask me

9
C/C assuming Java

• I assume you know how to program
• In Java
• Know basic programming
• Familiar with syntax (based on C)
• Understand OO concepts
• If not Java, then C?
• Probably need to brush up on OO
• Can still learn from first part of course
• None of the above? See me after class

10
Now some C.

• include ltstdlib.hgt
• include ltstdio.hgt
• int main (void)
• printf(Hello World\n)
• return EXIT_SUCCESS

11
C compilation
12
Whats in a header?

• Preprocessor definition
• define EXIT_SUCCESS 0
• Function prototypes
• Declare the argument/return types
• Example
• int factorial(int x)
• Note ends in semi-colon.
• External variable declarations (later)
• Type declarations (also later)

13
A first approximation

• / maybe this is the prototype from stdio?/
• void printf(string x)
• int main (void)
• printf(Hello World\n)
• return 0 / Replace defined symbol /

14
Close, but

• C doesnt have a string type
• char represents a sequence of characters
• printf actually
• Returns int (number of characters printed)
• Takes a variable number of arguments
• int printf(char format, )

15
A variable number of arguments?

• First arg format specifier string
• Contains directives (d, s, )
• Later args values to replace directives
• Example
• int x 3
• char s some string
• printf(x is d and s is s \n, x, s)

16
Basically right

• int printf(char format, )
• int main (void)
• printf(Hello World\n)
• return 0
• (Actually, lots of other stuff defined in those
  headers)

17
Two types of include

• include ltstdio.hgt
• Use angle brackets for system files
• include myheader.h
• Use quotes for header files in the local
  directory (i.e. that you wrote/were provided)

18
So whats like Java?

• Most basic syntax
• int i
• int counter 0
• for ( i 0 i lt 10 i )
• if (xi lt yi)
• counter
• return counter

19
Caveat

• What about
• for (int i 0 i lt 10 i )
• Error for loop initital declaration used
  outside C99 mode
• Solution compile with -stdc99

20
Arrays somewhat similar

• Indexed the same xi
• Not objects dont have length field
• Just contiguos regions of memory
• Accesses not bounds checked
• Dynamic allocation is different
• (more on this later)

21
Editing/compiling code

• ssh guide on class webpage how to login
• Editing
• On eniac-l
• Emacs guide on web
• Other editor of your choice on your own
• On your computer your choice of editor
• Compile with cygwin or other compiler?
• Copy to eniac-l to test.

22
Homework 1

• On webpage now
• Due Wed Jan 30th at noon by email
• Probably lt 40 minutes
• Get acquainted with Javalike parts of C
  discussed today
• Questions? email me.

23
Questions?