This presentation is credited by the author. It talks about the history of C language, how to learn and write simple C syntax.

1. C programming Language
and
Data Structure
BSIS Freshmen – Semi
Final Topic
Compiled and Illustrated by: MJLADO

2. Language?
Source of Communication between two persons.
– Example: Human –To- Human
OR
Source of Communication between User and
Computer is called programming language.
– Example: Human –To- Machine

3. Program
Set of instructions which perform any specific
task is called program.

4. What is programming?
Series of instructions to a computer to achieve a task
Instructions must be written in a way the computer can understand
Programming languages are used to write programs
Once the code (language) of a program has been written, it must be
executed (run, started).
Some programming languages (like C, C++ or Java) require the
code to be compiled (translated to binary) before it can be started.

5. History of C language
Year Language Developer
1960
ALGOL
(Algorithmic Language)
Internal Committee
1967
BCPL
(Basic Combined Programming Language)
Martin Richards
1970 B Ken Thompson
1972 C Dennis Ritchie

6. What is C?
C
A language written by Dennis Ritchie in
1972 at AT&T Bell Labs USA. 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.

7. Why C Still Useful?
C provides:
Efficiency, high performance and high quality
Provide functionality through rich set of function libraries
Gateway for other professional languages like C  C++  Java
C is used:
System software, Compilers, Editors
Graphics and Geometry
Databases, operating systems, device drivers
Also used in application programs

8. Software Development Method
Requirement Specification
– Problem Definition
Analysis
– Refine, Generalize the problem definition
Design
– Develop Algorithm: (A formula or set of steps for solving a particular problem)
Implementation
– Write Code
Verification and Testing
– Test and Debug the code

9. How do you write a program?
Decide what steps are needed to complete the task
Write the steps (Algorithm) in pseudo code (written in English) or as a
flowchart (graphic symbols)
Translate into the programming language
Try out the program and “debug”.

10. Sample Pseudo code
Task: add two numbers
Pseudo code (Algorithm) :
1. Start
2. Get two numbers
3. Add them (a + b)
4. Print the answer
5. End

11. What does a flowchart look like?
Pseudo code (Algorithm)
:
1. Start
2. Get two numbers
3. Add them (A + B)
4. Print the answer
5. End
Start
Get 2 numbers
A+B
Print answer
End

12. START/END
INPUT/OUTPUT
PROCESS
DECISION
Flow Chart symbols

13. Integrated Development Environments
An integrated development environment (IDE) is a software package that
makes it possible to edit, compile, link, execute, and debug a program without
leaving the environment.
13

14. Simple C Program
/* A first C Program*/
#include <stdio.h>
#include <conio.h>
void main()
{
clrscr();
printf("Hello World");
getch();
}

15. Simple C Program
/* A first C Program*/
#include <stdio.h>
#include <conio.h>
void main()
{
clrscr();
printf("Hello World");
getch();
}
Header File
Main Function
Opening bracket
Statement Part
Closing Bracket
Preprocessor directive
Clear Data
Get the Data

16. Simple C Program
Line 1: #include <stdio.h> and #include <conio.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 and conio.h.
This file contains declarations for functions that the program needs
to use. A declaration for the printf function is in this file.

17. 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 finish some
task.
The "void" specifies the return type of main. In this case, nothing is
returned to the operating system.

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

19. Simple C Program
Line 4: clrscr();
This will allow the program to avoid data redunduncy.

20. Simple C Program
Line 5: printf("Hello World ");
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.
If there were another printf in this program, its string would print on
the next line.

21. Simple C Program
Line 6: getch();
This will allow the program to get the data from the given
instructions.

22. Simple C Program
Line 7: }
This closing bracket denotes the end of the program.

23. Comment
Comment should be enclosed between /* */
It is used to increase the readability of the program.
Any number of comments can be given at any place in the
program.
example:
/* A first C Program*/

24. Steps in learning English language
Steps in learning C
Alphabets
Digits
Special-symbols
Constants
Variables
Keywords
Instruction Program
Getting started with C
Alphabets Sentences ParagraphWords

25. The C character Set
• A character denotes any alphabet, digit or
special symbol used to represent information.
Alphabets A,B, …. ,Y, Z
a,b, ….. ,y, z
Digits 0,1,2,3,4,5,6,7,8,9
Special Symbols ~ ‘ ! @ # % ^ & * ( ) _ - + =
| { } [ ] : ; “ ‘ < > , . ? /

26. Constants, Variable and keywords
The alphabets, numbers and special symbol when properly
combined form constants, variables and keywords
A constant is a quantity that doesn’t change
A variable is a name given to the location in memory where
the constant is stored
Example: 3x + y = 20
3 & 20 are constants, which cannot change
x & y can vary or change hence are called variables

27. Keywords
• Keywords are the words whose meaning has already been
explained to the C compiler
• Sometimes called reserved words.
• They cannot be used as variable names.
• There are only 32 keywords available in c
auto double if static do
break else int struct goto
case enum long switch signed
char extern near typedef while
const float register union default
continue far return unsigned for
short void

28. Escape Sequence
Certain non printing characters can be expressed in terms of escape
sequences
n new line
t tab
a alert
backslash
” double quote
0 Null
b Backspace

29. Data Types
• C Supports several different types of data, each of
which may be represented differently within the
computers memory.
• Basic data types are listed below:
Data Type Description Typical Memory
int integer quantity 2 bytes
char single character 1 bytes
float floating point number 4 bytes

30. Escape Sequences in C
Certain non printing characters can be expressed in terms of escape
sequences
Character Escape Sequence
bell a
backspace b
horizontal tab t
vertical tab v
newline n
carriage return r
quotation mark (“) ”
question mark(?) ?
backslash ()
null 0

31. 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: The object code of a program is linked with libraries that are needed
for execution of a program. The linker is used to link the program with libraries.
It creates a file with '*.exe' extension.

32. Program Development
Source File
Program Object Code File
Executable File
Preprocessor
Modified Source Code in RAM
Compiler
Linker
Editor

33. Keywords
Sometimes called reserved words.
Are defined as a part of the C language.
Can not be used for anything else!
32 keywords in C
Examples:
– Int
– void
– while
– for