1. Introduction to C Programming

2. Books
“The Waite Group’s Turbo C Programming for PC”, Robert Lafore, SAMS
“C How to Program”, H.M. Deitel, P.J. Deitel, Prentice Hall

3. Programming languages
Various programming languages
Some understandable directly by computers
Others require “translation” steps
Machine language
Natural language of a particular computer
Consists of strings of numbers(1s, 0s)
Instruct computer to perform elementary operations one at a time
Machine dependant

4. Programming languages
Assembly Language
English like abbreviations
Translators programs called “Assemblers” to convert assembly language programs to machine language.
E.g. add overtime to base pay and store result in gross pay
LOAD BASEPAY
ADD OVERPAY
STORE GROSSPAY

5. Programming languages
High-level languages
To speed up programming even further
Single statements for accomplishing substantial tasks
Translator programs called “Compilers” to convert high-level programs into machine language
E.g. add overtime to base pay and store result in gross pay
grossPay = basePay + overtimePay

6. History
In 1972 Dennis Ritchie at Bell Labs writes C and in 1978 the publication of The C Programming Language by Kernighan & Ritchie caused a revolution in the computing world
In 1983, the American National Standards Institute (ANSI) established a committee to provide a modern, comprehensive definition of C. The resulting definition, the ANSI standard, or "ANSI C", was completed late 1988.

7. History of C Evolved from two previous languages BCPL , B
BCPL (Basic Combined Programming Language) used for writing OS & compilers
B used for creating early versions of UNIX OS
Both were “typeless” languages
C language evolved from B (Dennis Ritchie – Bell labs)
Typeless – no datatypes. Every data item occupied 1 word in memory.
** Typeless – no datatypes. Every data item occupied 1 word in memory.

8. Characters of C Hardware independent
Programs portable to most computers
Dialects of C
Common C
ANSI C
ANSI/ ISO 9899: 1990
Called American National Standards Institute ANSI C
Case-sensitive

9. What is C? C
A language written by Brian Kernighan and Dennis Ritchie. This was to be the language that UNIX was written in to become the first "portable" language
In recent years C has been used as a general-purpose language because of its popularity with
programmers.

10. Why use C?
Mainly because it produces code that runs nearly as fast as code written in assembly language. Some examples of the use of C might be:
Operating Systems
Language Compilers
Assemblers
Text Editors
Print Spoolers
Network Drivers
Modern Programs
Data Bases
Language Interpreters
Utilities
Mainly because of the portability that writing standard C programs can offer

11. Why C Still Useful? C provides: C is used:
Efficiency, high performance and high quality s/ws
flexibility and power
many high-level and low-level operations  middle level
Stability and small size code
Provide functionality through rich set of function libraries
Gateway for other professional languages like C  C++  Java
C is used:
System software Compilers, Editors, embedded systems
data compression, graphics and computational geometry, utility programs
databases, operating systems, device drivers, system level routines
there are zillions of lines of C legacy code
Also used in application programs

12. Software Development Method
Requirement Specification
Problem Definition
Analysis
Refine, Generalize, Decompose the problem definition
Design
Develop Algorithm
Implementation
Write Code
Verification and Testing
Test and Debug the code

13. Development with C Four stages
Editing: Writing the source code by using some IDE or editor
Preprocessing or libraries: Already available routines
compiling: translates or converts source to object code for a specific platform source code -> object code
linking: resolves external references and produces the executable module
Portable programs will run on any machine but…..
Note! Program correctness and robustness are most important than program efficiency

14. C Standard Library Two parts to learning the “C” world Learn C itself
Take advantage of rich collection of existing functions called C Standard Library
Avoid reinventing the wheel
SW reusability

15. Basics of C Environment
C systems consist of 3 parts
Environment
Language
C Standard Library
Development environment has 6 phases
Edit
Pre-processor
Compile
Link
Load
Execute

16. Basics of C Environment
Editor
Disk
Phase 1
Program edited in
Editor and stored
on disk
Preprocessor
Disk
Phase 2
program processes
the code
Compiler
Disk
Phase 3
Creates object code
and stores on disk
Linker
Disk
Phase 4
Links object code
with libraries and
stores on disk

17. Basics of C Environment
Loader
Phase 5
Puts program in
memory
Primary memory
CPU
Phase 6
Takes each instruction
and executes it storing
new data values
Primary memory

18. Simple C Program /* A first C Program*/ #include <stdio.h>
void main()
{      printf("Hello World \n"); }

19. Simple C Program Line 1: #include <stdio.h>
As part of compilation, the C compiler runs a program called the C preprocessor. The preprocessor is able to add and remove code from your source file.
In this case, the directive #include tells the preprocessor to include code from the file stdio.h.
This file contains declarations for functions that the program needs to use. A declaration for the printf function is in this file.

20. Simple C Program Line 2: void main()
This statement declares the main function.
A C program can contain many functions but must always have one main function.
A function is a self-contained module of code that can accomplish some task.
Functions are examined later.
The "void" specifies the return type of main. In this case, nothing is returned to the operating system.

21. Simple C Program Line 3: {
This opening bracket denotes the start of the program.

22. Simple C Program Line 4: printf("Hello World From About\n");
Printf is a function from a standard C library that is used to print strings to the standard output, normally your screen.
The compiler links code from these standard libraries to the code you have written to produce the final executable.
The "\n" is a special format modifier that tells the printf to put a line feed at the end of the line.
If there were another printf in this program, its string would print on the next line.

23. Simple C Program Line 5: }
This closing bracket denotes the end of the program.

24. Escape Sequence \n new line \t tab \r carriage return \a alert
\\ backslash
\” double quote

25. Memory concepts Every variable has a name, type and value
Variable names correspond to locations in computer memory
New value over-writes the previous value– “Destructive read-in”
Value reading called “Non-destructive read-out”

26. Variables and data types
1. Data type determines how much storage space is allocated to variables.
2. Data type determines the permissible operations on variables.
3. The variables should be declared by specifying the data type.
4. There is a family of integer data types and floating-point data types.
5. Characters are stored internally as integers.
6. Characters are interpreted according to the character set.
7. The most commonly used character set is ASCII.
8. In the ASCII character set, A is represented by the number 65.

28. A single character stored in one byte.
char c;
c is a char variable you canstore the letter A
c='A‘

29. /* elementary data types */
char 1 byte
int 2 bytes
Short 2 bytes
long 4 bytes
double 4 bytes
float 4 bytes
/* non-elementary or customized data types */
struct not defined
Enum 2 bytes /* considered as int */

30. Arithmetic in C C operation Algebraic C Addition(+) f+7 f+7
Subtraction (-) p-c p-c
Multiplication(*) bm b*m
Division(/) x/y, x , x y x/y
Modulus(%) r mod s r%s

31. Precedence order
Highest to lowest ()
*, /, %
+, -

32. Example Algebra: z = pr%q+w/x-y C: z = p * r % q + w / x – y ;
Precedence:

33. Example Algebra: a(b+c)+ c(d+e) C: a * ( b + c ) + c * ( d + e ) ;
Precedence:

34. Decision Making Checking falsity or truth of a statement
Equality operators have lower precedence than relational operators
Relational operators have same precedence
Both associate from left to right

35. Decision Making Equality operators == != Relational operators <
>
<=
>=

36. Summary of precedence order
Operator Associativity
() left to right
* / % left to right
left to right
< <= > >= left to right
== != left to right
= left to right

37. Assignment operators = += -= *= /= %=

38. Increment/ decrement operators

39. Increment/ decrement operators
main() {
int c;
c = 5;
printf(“%d\n”, c);
printf(“%d\n”, c++);
printf(“%d\n\n”, c);
printf(“%d\n”, ++c);
return 0; } 5 6

40. Thank You
Thank You