1. C programming Language
For SSUET- Electronic Students

2. Introduction to C Programming

3. Books “Turbo C Programming for PC”, Robert Lafore, SAMS
Teach Yourself C : Herbert Schildt

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

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

6. 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.

7. 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

8. 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.
AT&T-American Telephone and Telegraph
UNIX-Uniplexed Information and Computing System or Service

9. Why C Still Useful? C provides: C is used:
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

10. 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

11. 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”.

12. Getting started with C Steps in learning English language
Steps in learning C
Alphabets
Sentences
Paragraph
Words
Alphabets
Digits
Special-symbols
Constants
Variables
Keywords
Instruction
Program
Programming with C 12

13. Sample Pseudo code Task: add two numbers Pseudo code (Algorithm) :
Start
Get two numbers
Add them (a + b)
Print the answer
End

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

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

16. 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. 16

17. Header Files
The files that are specified in the include section is called as header file
These are precompiled files that has some functions defined in them
We can call those functions in our program by supplying parameters
Header file is given an extension .h
C Source file is given an extension .c

18. Main Function This is the entry point of a program
When a file is executed, the start point is the main function
From main function the flow goes as per the programmers choice.
There may or may not be other functions written by user in a program
Main function is compulsory for any c program

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

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

21. 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.

22. Simple C Program Line 2: void main(void)
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.

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

24. Simple C Program Line 4: 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.

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

26. Comment Single line comment // (double slash)
– Termination of comment is by pressing enter key
Multi line comment
/*….
…….*/
It is used to increase the readability of the program.
Any number of comments can be given at any place in the program.
Comment cannot be nested
example:
/* A first C Program*/
Comment about the program should be enclosed within /* */
nested comments eg /* to calculate the simple interest /* compound interest */ */ is invalid
comment can be split over more than one line eg
/* to calculate the
simple interest
and the compound
interest */
This comment statements will be ignored by the compiler while compiling the program, i.e this comment statement won’t be converted to object code.
Programming with C 26

27. Running C Program Type a program Save it
Compile the program – This will generate an exe file (executable)
Run the program (Actually the exe created out of compilation will run and not the .c file)
In different compiler we have different option for compiling and running. We give only the concepts.

28. 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 ,1,2,3,4,5,6,7,8,9
Special Symbols ~ ‘ # % ^ & * ( ) _ - + =
| \ { } [ ] : ; “ ‘ < > , . ? /
Programming with C 28

29. 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
A constant is a quantity that doesn’t change. This quantity can be stored at a locations in the memory of the computer.
Eg 3x + y = 20
3 & 20 are constants, which cannot change
x & y can vary or change hence are called variables
Programming with C 29

30. 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
Programming with C 30

31. 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

32. 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 bytes
char single character bytes
float floating point number bytes
Programming with C 32

33. Escape Sequences in C Character Escape Sequence
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
Programming with C 33

34. 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.

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

36. 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