COMP 4/6262:
Programming UNIX
Lecture 21
C Programming Tools
April 17, 2006
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Guidelines and tips
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Introduction to Computer Programming Tools - Study Guide | COMP 4262, Study notes of Computer Science
Material Type: Notes; Class: Programming UNIX; Subject: COMP Computer Science; University: University of Memphis; Term: Spring 2006;
Typology: Study notes
Pre 2010
1 / 72
This page cannot be seen from the preview
Don't miss anything!
Related documents
Partial preview of the text
Download Introduction to Computer Programming Tools - Study Guide | COMP 4262 and more Study notes Computer Science in PDF only on Docsity!
- COMP 4/6262: Programming UNIX Lecture 21 C Programming Tools April 17,
Outline {
Unix programming philosophy
{
C programming tools
z
compilation
{
single-module programs {
multi-module programs
z
debugging
z
maintaining large multi-module programs
{
the unix file dependency system: make {
the unix archive system: at {
the unix source code control system: sccs
{
Chapter 12, Glass and Ables
{
Source code available: ftp://ftp.prenhall.com/pub/esm/the_apt_series.s-042/glass_ables_unix-3e/
Preferred UI style
Graphical user interfaces (GUI)
vs
Command line interfaces (CLI)
{
What are the consequences of GUIs or
CLIs? {
We know that a poor GUI can make using a
system hard for a novice (or even an expert) {
What happens when the CLI is weak?
Command line interfaces
A weak or nonexistent CLI can lead to problems: {
Outputs can’t be used as inputs {
Remote system access will be difficult {
Non-interactive programs (servers, daemons, and background processes) will require a GUI How do Windows/Mac OS handle these tasks? (Hint: They’re actually moving towards CLIs!)
Unix philosophy 9.
Rule of Representation: Fold knowledge into data soprogram logic can be stupid and robust.
Rule of Least Surprise: In interface design, always do theleast surprising thing.
Rule of Silence: When a program has nothing surprising tosay, it should say nothing.
Rule of Repair: When you must fail, fail noisily and as soonas possible.
Rule of Economy: Programmer time is expensive; conserveit in preference to machine time.
Rule of Generation: Avoid hand-hacking; write programs towrite programs when you can.
Rule of Optimization: Prototype before polishing. Get itworking before you optimize it.
Rule of Diversity: Distrust all claims for “one true way”.
Rule of Extensibility: Design for the future, because it willbe here sooner than you think.
C compilation
{
Compilation
z
Preprocessing
z
Compiling
z
Assembling
z
Linking
{
Text source goes in, executablebinaries come out
Single-model program {
example
z
reverse a string
{
write
z
lecCh12/reversefirst.c
{
compile+link
z
gcc reversefirst.c
(output file: a.out)
z
gcc reversefirst.c –o reversefirst
{
execute
z
reversefirst
Preprocessing
{
The preprocessor takes a C (or C++) file and
translates directives into source code {
Directives are used to make programs
compact and portable to different environments {
They include:
z
#define, #include, #ifdef
z
‘#’ must be the first non-whitespace character
{
Note that directives are not terminated by ‘;’!
More macros
So, the following code segment: #define
test(
f1,
f
f
f
x
test(6,
y
test(x,
Is preprocessed into this before compilation: x
y
x
Compiling & Assembling
{
The compiler translates the preprocessed source intotext assembly language files (often “.s” on Unix, or“.asm” on Windows)
{
The assembler takes the assembly file and translatesinto machine code, in binary object files (“.o” on Unix,“.obj” on Windows)
{
Object files have multiple sections, such as forinstructions and data, and are machine specific
Separating the stages
{
With most compilation systems, it is possible to
perform all of these steps separately {
Why? You may want to use different programs for
particular parts of the process. with g++: -E = only preprocess, do not compile -S = stop after compile, do not assemble -c = compile/assemble, but do not link
Multi-module programs
{
Large software systems are divided inmultiple files
z
library files contain reusable functions
z
those functions are usually used from differentmain programs
{
Each file can be compiled separately intoobject files
{
The object files can be linked together intoan executable
Compiling
{
We can compile each source code fileseparately using the
–c
of cc
>gcc –c reverse.c >gcc –c main1.c
{
As an alternative you can list all the sourcecode files in one line
>gcc –c reverse.c main1.c
{
An object file .o is generated for everysource code file specified
Linking
{
To link the object files into inexecutable type
gcc reverse.o main1.o –o main
{