Introduction to C Language

1. Introduction to C

2. What is a program
• A sequence of instructions that a computer can
interpret and execute;
– If I tell you the way from IBA Academic Block to
IBA Administration Block … I will tell sequence of
instructions…. Any wrong instruction leads to a
undesired result.
• A program is something that runs on your computer.
In case of MS Windows program is of .EXE or .COM
extensions
• MS Word, Power point, Excel are all computer
programs
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Aftab Ahmed Palh - Computer Science
Instructor

3. Introduction to C
• C is a statically typed, compiled, general-purpose,
case-sensitive, free-form programming language.
• It supports procedural, object-oriented, and generic
programming.
• C is regarded as a middle-level language, as it
comprises a combination of bot h high-level and low-
level language features
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Aftab Ahmed Palh - Computer Science
Instructor

4. Introduction to C++ (Cont..)
• C++ was developed by Bjarne Stroustrup starting in
1979 at Bell Labs in Murray Hill, New Jersey.
• C++ is an enhancement to the C language and
originally named C with Classes but later it was
renamed C++ in 1983.
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Aftab Ahmed Palh - Computer Science
Instructor

5. Introduction to C++ (Cont..)
Object- Oriented Programming
• C++ fully supports object-oriented programming,
including the four pillars of object-oriented
development:
• Encapsulation
• Data hiding
• Inheritance
• Polymorphism
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Aftab Ahmed Palh - Computer Science
Instructor

6. The ANSI Standard
• The ANSI standard is an attempt to ensure that
C++ is portable -- that code you write for
Microsoft's compiler will compile without errors,
using a compiler on a Mac, UNIX, a Windows box,
or an Alpha.

7. Use of C++
.
• C++ is used by hundreds of thousands of
programmers in essentially every application
domain.
• C++ is being highly used to write device drivers
and other softwares that rely on direct
manipulation of hardware under real-time
constraints

8. Environment Setup
• Before you start doing programming using C++, you
need the following two softwares available on your
computer.
1. Text Editor
2. C++ Compiler
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Aftab Ahmed Palh - Computer Science
Instructor

9. Environment Setup Cont…
• The files you create with your editor are called
source files, and for C++ they typically are named
with the extension .cpp
• C++ compiler, which will be used to compile your
source code into final executable program
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Aftab Ahmed Palh - Computer Science
Instructor

10. Writing C++ Programs
• A programmer uses a text editor to create or modify
files containing C++ code.
• Code is also known as source code.
• A file containing source code is called a source file.
• After a C++ source file has been created, the
programmer must invoke the C++ compiler before
the program can be executed (run).
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Aftab Ahmed Palh - Computer Science
Instructor

11. Compiler converts
human readable
language to a
language which is
understandable by
the operating
system/hardware
Examples of C/C++
compilers of today:
Visual C++
GCC/G++
DJGPP (open source
for windows like
GCC)
Borland C
Turbo (obsolete and
not recommended)
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Aftab Ahmed Palh - Computer Science
Instructor

12. Program Development
Source File
Program Object Code File
Executable File
Preprocessor
Modified Source Code in RAM
Compiler
Linker
Other Object Code Files (if any)
Editor
12
Aftab Ahmed Palh - Computer Science
Instructor

13. A Simple C++ Program
#include <iostream.h> //This is preprosessor directive
int main ( ) //this tells the starting point of your program
{
cout << “Hello World” <<endl ; //print the text on monitor
return 0 ; //return to operating system
}
Note: cout is an object given to you by the creators of C++. This function saves you
From the complexity of writing your own function of how to display text on the computer
Screen. Hence you are more productive with the actual program rather than worrying
About such issues.
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Aftab Ahmed Palh - Computer Science
Instructor

14. Elements of C+ Program
Preprocessor Directive
• Preprocessor Directive tells computer to load
contents of a certain file
• #include
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Aftab Ahmed Palh - Computer Science
Instructor

15. Elements of C+ Program
Header file
• Header file contains the implementation code
of the c++ functions and c++ keywords.
• Iostream.h, conio.h, stdio.h
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Aftab Ahmed Palh - Computer Science
Instructor

16. 16
Elements of C+ Program
• int main()
– C++ programs contain one or more functions, exactly
one of which must be main
– Parenthesis used to indicate a function
– int means that main "returns" an integer value
– Braces { and } indicate a block
• The bodies of all functions must be contained
in braces
– Braces indicate the block of function in c++ program
Aftab Ahmed Palh - Computer Science
Instructor

17. 17
Elements of C+ Program
• return 0;
– A way to exit a function
– return 0, in this case, means that the program
terminated normally
• Linker
– When a function is called, linker locates it in the
library
– Inserts it into object program
– If function name is misspelled, the linker will produce
an error because it will not be able to find function in
the library
Aftab Ahmed Palh - Computer Science
Instructor

18. 18
Elements of C+ Program
• Parenthesis ()
• Parenthesis are used to declare function.
Example Int main()
• Cout
• Cout is a keyword which displays the result of
program on monitor screen
• Cout<<“hello”;
Aftab Ahmed Palh - Computer Science
Instructor

19. 19
Elements of C+ Program
• Int
• Int is a data type of function or variable
• Semicolon ;
• Semicolon is used to end the program
statement.
• Program Statement
• Program statement or simply statement is the
instruction in c++ programming language
Aftab Ahmed Palh - Computer Science
Instructor