CPS120: Introduction to Computer Science

1
CPS120 Introduction to Computer Science

• Compiling Your First Program

2
Compilers

• An engine that works on your behalf to process
  instructions and allow you to deal with various
  basic rules of the language
• The compilers job is to make sure you follow the
  rules, to require that you provide enough
  information that the compiler can translate you
  instructions into languages the components can
  understand

3
Compilers Available

• Products range from freeware compilers to work
  environments designed for commercial application
  development
• Borland C compiler
• CodeWarrior
• IBM Visual Age C
• Microsoft Visual C
• GNU freeware
• DJGPP freeware (  www.delorie.com/djgpp/ )

4
Compilation Process

1. Get the set of instructions from you
2. Review the instructions to see if they violate
   the rules (syntax) of the language
3. If all the rules are obeyed, create a working
   file in the language of the computer (machine
   language)
4. Attach to the working file full instructions for
   any shortcuts you may have used (linkage)
5. Assemble a final file in machine language

5
Compiler Files

• Source code
• Linked/Library file
• Object file
• Executable file

6
Source Code

• The set of instruction that you will develop on
  your own for processing by the compiler

7
Executable Files

• A machine-language executable file created when
  the compilation process is complete
• All that is needed to run the program
• Not human-readable
• Has the extension .EXE
• Stored in binary form
• Copies may be distributed (portable)
• Known as an application

8
Compiling and Debugging

• Executable code will not be created until you
  correct all of the syntax errors in your source
  code
• Then the fun (with logic errors) begins

9
Creating Source Code Files

• Actually Compiling a Program

10
Creating Source Code

• Programmers spend most of their time with source
  code files
• Need to be comfortable with an editor that
  creates ASCII text files
• 7-bit representation of all keyboard character
• Dont use a word processor
• If an editor in an environment is available, use
  that, it provides more sophisticated tools

11
Using the Editor

• Save often because there is no autosave in Visual
  C
• The editor will do matching of delimiters and
  intelligent indentation

12
C Usages Conventions

• C is absolutely case sensitive
• For Instance A is 97 in ASCII and a is 65
• Remember in ASCII , , and ( are not equivalent
• No keywords in ANSI standard are even partially
  uppercase
• While is not a keyword, while is
• Be careful if you define new keywords
• The most common practice in C is to use small
  letters of the first part of a variable name and
  capitals for the rest of it

13
Comments

• Document what is happening, why it is happening
  and other issues
• Commentary is ignored by the compiler
• C has inline, block and documentary comments
• Inline comments are within line of code
• Use the // symbols
• Block comments are long comments delimited with
  / and /

14
Scope Delimiters

• A symbol or pair of symbols used to define a
  region or area which is considered a locale
• In programming, many structures need to have
  their scope defined because they should not
  affect the entire program
• In C, the symbols and are used

15
Literals

• Literals are system commands and other pieces of
  information that the compiler doesnt understand,
  and therefore, takes your word for them
• In C, literals are enclosed in straight double
  quotes " " which is the shift of the apostrophe

16
Columns and White Space

• Modern programming languages are free form with
  delimiters instead of columns to determine the
  end of instructions
• The (semi-colon) is the delimiter used in C
• Use tabs, indents, and blank lines in any manner
  that makes code easier to understand
• Many programming instructions become subordinate
  to other instructions due to scope and other
  restrictions. Formatting code to reflect this
  makes it easier to read

17
Variables

• Variables or identifiers are used to hold
  information
• Usually mixed case with the first letters small
  and the rest starting with a capital
• e.g. theWeight

18
Color Coding in Visual C Editor

• Comments are green and are ignored by the
  compiler
• All ANSI keywords are coded in blue
• Other code is in plain black
• Compiler keywords like cin and cout are also
  shown in black

19
Setting Up a Visual C Workspace

• Left-click START
• In the program section, select Visual Studio or
  Visual C (depending on what is installed)
• Left click on the Visual C icon to load the
  environment
• Create a new work area by choosing FILE/NEW
• Choose FILES tab
• Click on the C Source File to reach the editor
• Add a filename and directory before continuing
• e.g. c/cppFun/myFirstCpp

20
Setting Up a Visual C Workspace

1. Create the directory with START / EXPLORE
2. Double-click the drive letter
3. Choose FILE, NEW FOLDER
4. Left click on FOLDER
5. Change new folder to cppFUN
6. Close Explorer with the X
7. Back in Visual C, type myFirstCpp in the file
   box
8. Click OK and get back to the main edit screen

21
Setting Up a Visual C Workspace

1. Enter the source code
2. After entering the program, FILE then SAVE

22
Why Create New Subdirectories?

• You should always use subdirectories to store
  your files. Visual C creates quire a few work
  files when it generates the executable file for
  you source code, and they will be easy to dispose
  of if you keep everything together in one
  convenient place.
• Under no circumstances should you use the root
  (C\) directory except on a floppy disk (A\).

23
Running the Program

1. Press the REBUILD ALL button. It has two arrows
   in a box
2. Press the RUN button. It is a red exclamation
   point

24
Disk Space Issues

• Text files are insignificant in terms of space
• However, six other files are created every time
  something is compiled some get around 95 full
• Highlighting the disk in are 3 or 4 times larger
  than the source
• You can delete anything but the file with the
  .cpp suffix everything else can be recreated

25
Recompiling

• Open the file by going the file you stored it in
  and double clicking on it
• Scan the source code for obvious errors before
  attempting to compile
• Attempt to compile using the COMPILE button or
  choosing the first option on the BUILD menu
• Answer Yes to use the default project workspace
• The lower window will be active and the compile
  will occur
• Note the number of errors and warnings
• These need to be dealt with before executable
  code is created

26
Working in a Lab Environment

• The following issues are magnified working in a
  laboratory environment
• Viruses
• Scan disks transferring between the lab and home
• Plagiarism
• Beware of shoulder surfing, temp directories,
  shared directories, discarded print and new print
• Name things vaguely and delete what you are done
  with
• Theft
• Take your floppies and Zip Disks with you
• Malicious mischief