CS 240 Programming in C and UNIX

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CS 240Programming in C and UNIX

• Lecturer Bob Wilson
• Office S-3-071
• Phone [phone]
• Email bobw_at_cs.umb.edu

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Course Objectives

• This course will teach you C Programming
• It also covers several other related topics
• UNIX Commands
• Compiler and Debugger
• MAKE and Makefiles
• UNIX File System and File Access
• UNIX Processes and Shells/Shell Scripts

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Motivation

• C is the language of choice for systems
  programming and embedded systems
• Number of Programmers by Language
• COBOL 3 million
• Visual Basic 1.5 million
• C/C 1.1 million
• Mastery of the material in this course may enable
  you to get a high paying job!

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Introduction

• Syllabus and Lecture Notes
• Web http//www.cs.umb.edu/bobw
• Required Textbooks
• The C Programming Language, 2nd Ed., Kernighan
  Ritchie
• UNIX for Programmers and Users, 2nd Ed., Glass
  Ables

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Introduction

• HW assignments
• Assignment write-ups will be on my website
• But HW must be done on our UNIX systems!
• All Homework MUST BE an Individual Effort
• You can answer questions for each other as long
  as you acknowledge any help that you receive from
  others
• BUT DONT HAVE OR LET ANYONE ELSE DO YOUR
  HOMEWORK FOR YOU!
• Dont change the owner, group, or mode on any of
  your homework directories or files!! (NO chown,
  chgrp, chmod!)
• If I discover any cheating, Ill follow school
  policy!

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Getting Started

• Fill out the CS240 Student Survey Form on the web
  page as soon as possible
• UNIX Account
• Apply for CS240 ASAP!
• (Science 3rd Floor UNIX Lab)
• Use Sun Blades in UNIX Lab
• Access to UNIX systems from your home PC
• Secure internet access is required now!
• Can not use TELNET or FTP for remote access!
• Must use Secure Shell 2 for remote access
• Can use Putty or SSH Communications S/W packages

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Getting Started (SSH 2)

• Putty (Officially Recommended by Systems Staff)
• http//www.puttyssh.org (Non Commercial
  Downloads)
• Download SSHSecureShellClient-3.2.5.exe
• SSH Communications (Recommended by me)
• http//www.ssh.com/support/downloads/secureshellwk
  
• Download Non-Commercial Version (.exe for
  Windows)
• Or http//ce.uml.edu/sshwinclient.exe
• Download and Execute Installer executable
• Student Recommended
• http//www.i-tree.org/gpl/ixplorer.htm
  (Windows)
• http//rsug.itd.umich.edu/software/fugu/ (MAC OS
  X)

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Getting Started (Editor)

• Editing source files is a requirement
• Learn to use a UNIX editor program
• vi a simple visual editor described in Glass
• emacs a more complex visual editor that can also
  be used as a complete development shell (also
  described in Glass)
• pico a simple text editor based on the pine
  email program ( I personally like this one!)

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Getting Started (Email)

• Use the UNIX program pine for your email
• Pine is supported by system staff UNIX mail
  program is not.
• Type command man pine for pine user
  documentation
• Type command pine to access email

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Communication

• You must monitor course web site and your UNIX
  email account for announcements!!
• To contact me
• Office S-3-071
• Office Hours
• Posted on my website
• UNIX finger bobw
• Email bobw_at_cs.umb.edu
• Phone/Voice Mail [phone] (UMB)
• or [phone] (Home) only if really stuck!

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Java versus C

• CS110 (Java) is a prerequisite for CS240!
• Java and C are both block structured languages
• Compound statements defined by braces
• Similar if-else, for/while loops, expressions,
  etc
• Java is Object-Oriented, C is only procedural
• Java and C syntaxes look deceptively similar
• However, many small annoying differences
• Close but different semantics/syntax can be
  confusing
• Learn C as a different language not just like
  Java!
• C99 is a bit closer to Java, but were not using
  it here!

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Java versus C

• Java Compiler / Interpreter
• Java source is compiled to byte code file
  (.class)
• Byte code file is then interpreted by JVM
• JVM is written in native machine code
• Interprets program slower than native machine
  code
• C Compiler / Linker
• C source is compiled to object file(s)
• Object file(s) is/are linked to create an
  executable file
• Executable file runs as native machine code
• Executes program faster than interpreting byte
  code file

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C programming

• You will be learning to write, execute, and debug
  C language programs in this course
• We will not be just modifying programs that have
  already been written and debugged!!
• We will spend most of the time in class on the C
  language, MAKE, and the debugger
• This is the primary material for tests/quizzes
• Use Kernighan and Ritchie (KR) textbook!!

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UNIX Operating System

• You will be using UNIX to edit, compile, debug,
  and run your C programs.
• We will not spend as much time in class on UNIX.
• You must learn to use UNIX as you go
• You can be held accountable for UNIX on exams
• Use UNIX Guide and Glass textbook
• Also can refer to the Umass Boston Website
• http//www.cs.umb.edu/helproot/cs.guide/csguide/cs
  guide.html

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Basic UNIX Commands(Responsible for these next
time)

• cat display a file on your terminal screen (see
  also more)
• cd change directory
• cp copy a file
• logout logout from your account
• lpr print a hard copy
• ls list files in a directory
• man xxx manual page for command xxx
• more display a file on your terminal screen - one
  page at a time
• mv move a file from one place to another
• mkdir create a new subdirectory
• pwd print working directory (pathname of
  directory youre in)
• rm remove (delete) a file
• rmdir remove (delete) a directory
• CTRL-c Control key and c key together stop
  current command

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UNIX File System
Directory
bobw
cd cs240
cd ..
Sub-directory
bobw/cs240
pwd
ls
bobw/cs240/hw0
Sub-directory
File
bobw/cs240/hw0/assignment
File
rm filename
New Sub-directory
mkdir
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Hello World!

• Your first homework project is to create and run
  a C program Hello World! (KR, p5)
• Create a source file hello.c in one of three
  ways
• Use Unix Systems in UNIX Lab with vi, pico, or
  emacs
• Use Putty/SSH on PC to access UNIX with vi, pico,
  or emacs
• Use Notepad on your own PC and transfer the file
• Use gcc to compile and create a file named
  hello
• Run hello to see the printout on screen
• Use a typescript file to turn in assignments

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hello.c (KR, Page 6)

• / hello.c first homework assignment
• name your name
• date xx/xx/xx
• /
• include ltstdio.hgt
• int main( ) / well ignore arguments to main
  for now /
• printf(Hello World!\n)
• return 0

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C Source - Comment Lines

• Comment text is ignored by the compiler
• / This is a multi-line comment.
• The compiler ignores both lines. /
• Be sure to include the closing /
• / This is a multi-line comment
• int main ( )
• printf (Hello World!)
• return 0
• / terminated by this -gt /

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C Source - include

• Because this program uses the Standard I/O
  Library, it needs to include ltstdio.hgt
• In C programming, a .h file defines
• Macros (e.g. Names for constants)
• Prototypes for functions (e.g. printf itself)
• gcc wont compile hello.c with printf
  function without the include ltstdio.hgt

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C Source Main Declaration

• int main ( ) is the function where the UNIX
  system starts execution of your program
• Your functions code is within braces
• Braces are usually placed on their own lines
• function statements are here

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C Source - printf

• The Standard I/O Library provides you with a
  function named printf ( )
• printf ( ) prints argument as text on screen
• Argument is the text between the parentheses
  (Hello World!\n)
• \n is a C convention for end of line
• (For open book tests, remember KR page 193)
• All C program statements end with a