Introduction to programming with c,

2
First Step to the 21st
Century
Literacy : Programming
First Step to the 21st
Century
Literacy : Programming

Introduction to C
 The C programming language was designed or invented by
Dennis Ritchie at Bell Laboratories in the early 1970s
 Influenced by
 ALGOL 60 (1960),
 CPL (Cambridge, 1963),
 BCPL (Martin Richard, 1967),
 B (Ken Thompson, 1970)
 Traditional C:
 The C Programming Language, by Brian Kernighan and
Dennis Ritchie, 2nd
Edition, Prentice Hall
 Referred to as K&R
 Standardized in 1989 by ANSI (American National Standards
Institute) known as ANSI C
3

4
The Father of C Programming
and UNIX
The Father of C Programming
and UNIX

Introduction to C
 C is a Middle-level language: suitable language for systems
programming
 It is a procedural or sequential language
 C is also called ELL or English like language
 C is easy to learn or understand
 It is a case sensitive language
 C is a small language: relies on a “library” of standard functions
 C is highly portable: means that c programs written for one
computer can be run on other computer with no modification.
 C is a permissive language: it assumes that you know what
you’re doing, so it allows you a wider degree of latitude than
many languages. It doesn’t mandate the detailed error-checking
found in other language
5

Strength of C
1. Portability: means that c programs written for one computer
can be run on other computer with no modification.
2. Robustness: it is a robust language which is rich in built in
functions and operators.
3. Easy to understand: it is called ELL as almost all the structures
are very much similar to English language.
4. Efficiency: intended for applications where assembly language
had traditionally been used.
5. Power: large collection of data types and operators
6. Flexibility: not only for system but also for embedded system
commercial data processing
7. Programs written in C is fast and efficient
8. Standard library
9. Integration with UNIX 6

Weakness of C
1. error-prone
2. Difficult to modify
3. Difficult to debug
4. It is difficult to write large codes or solve complex
problems in C
7

Basic Structure of C Programs
1. Documentation Section
2. Link section
3. Definition Section
4. Global Declaration Section
5. Main Function( )
{
1. Declaration part
2. Executable part
}
6. Subprogram section
User defined functions are build here
8

Basic Structure of C
1. Documentation section: it consists of a set of comment lines
giving the name of the program, the author, the purpose of the
program and how the program works. The intention is to
provide with some documentation or information so that the
program can be used or analyzed later.
2. Link section: it provides instruction to the compiler to link
functions from the system library.
3. Definition section: definition of all the symbolic constants are
goes here. (if any symbolic constants are used in the program)
4. Global declaration: global variables are declared here. The user
defined functions also can be declared here. (if any global
variables are used in the program)
9

Basic Structure of C
5. Main function section: every C program must have one main
function. This section contains two parts: declaration part and
executable part. These two parts must appear in between the
opening and closing curly braces. The declaration part
declares all the variables that are going to be used in the
executable part. The executable part contains the main
programming logical statements or algorithm statements.
The executable must contain at least one statement. All the
statements in the declaration and executable parts must end
with a semicolon (;). This section is the logical end of the
program.
6. Subprogram section: if necessary then user defined functions
are defined here or created here.(if user defined functions are
used)
10

Need to understand
 Concept of definition and declaration
 Declaration: it tells or declares the identity or type of
something. Like Rahim is a boy. It means Rahim is here
declared as a boy.
 Definition: it tells or defines the specific type. Like in
definition section we will define or describe what are the
characteristics of a boy or how the boy works.
11

Need to understand
 ( ) – is called the parenthesis
 { } – is called the curly braces
 [ ] – is called the bracket
 Parenthesis is used to denote a function
 Curly braces is used to create a body
 Every statement in C ends with a semicolon
12

A Simple C Program
/* This is the sample program to print a
message hello world. This is done by
course teacher */
#include <stdio.h>
#include <conio.h>
main ( )
{
clrscr();
printf(“Hello Worldn”);
getch();
} 13

How a C program is Executed ?
 A C program is executed in three phases:
1. Creating Source Code file
[ Empty file(input) Source Code File(output) ]
2. Compiling
[ Source Code File(input) Object File(output) ]
3. Linking
[ Object File(input) Executable File(output) ]
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How a C program is Executed ?
Creating Source
Code
Creating Source
Code
Compiling
Source Code
Compiling
Source Code
Linking Object
File
Linking Object
File
[ Source Code
File .c ]
[ Object File .obj ]
[ Executable File
.exe ]
[ Empty File ]
15

Step by step
procedure how a C
program is
executed
Step by step
procedure how a C
program is
executed
16

How a C program
is executed
?
How a C program
is executed
?
17

18
Md. Shakhawat Hossain
Student of Department of Computer Science &
Engineering
University of Rajshahi
E-mail: mshimul86@gmail.com

Introduction to programming with c,

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