Transcript Document

Introduction to C++
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Objectives of this session
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What is C++
A Simple Program
Comments in C++
Output Operator
Input Operator
Cascading of I/O Operator
Structure of a C++ Program
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C++
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C++ is an object-oriented programming
language.
Developed by Bjarne Stroustrup at AT&T Bell
Laboratories, USA in the early 1980’s.
Simule 67 + C language  C++
1997 November ANSI/ISO standards
committee standardised C++.
For developing editors, compilers, databases,
communication systems, etc.
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A Simple Program
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C++ works by giving (separate) instructions to the
computer.
These instructions can be written as functions.
The primary function used in C++ is called main. This
means that every C++ program should have the
main() function. Because a function is an assignment,
in order to perform its job, a function has a body. The
body of a function starts with an opening curly bracket
"{" and closes with a closing curly bracket "}".
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A Simple Program
// my first program in C++
#include <iostream.h>
int main ( )
{
cout << "Hello World!";
return 0;
}
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Hello World!
continue…
Comments in C++
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The most basic documentation you have to perform is
to put comments as much as you can. Comments help
you and other people who read your code to figure out
what you were doing.
Comments are not read by the compiler while
executing your program.
C++ supports two ways to insert comments:
o
o
// line comment
/* block comment */
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Comments in C++
continue…
// The hello.cpp program
// Include the iostream library
#include <iostream.h>
int main( )
{
/* Here is a simple sentence that I want to display when the
program starts. It doesn't do much. I am planning to do more stuff
in the future. */
cout << "Hi, this is my program!";
return 0;
}
// The end of my program
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Output Operator
cout << "Hi, this is my program!";
cout is a predefined object that represents the standard
output stream in C++, here the standard output stream is
screen.
scree
n
<<
cout
Object
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Insertion Operator
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C++ variable
scree
n
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Output Operator
cout
<<
Object
Insertion Operator
continue…
C++ variable
The operator << is called insertion or put to operator.
It inserts ( or sends ) the contents of the variable on its right to
the object on its left.
cout << "Hi, this is my program!";
cout << number ;
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Input Operator
cin >> number1;
cin is a predefined object that corresponds to the standard
input stream in C++, here the standard input stream is
keyboard.
Object
Extraction Operator
C++ variable
cin
>>
50.55
Keyboard
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Input Operator
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Object
Extraction Operator
C++ variable
cin
>>
50.55
Keyboard
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The operator >> is known as extraction or get from
operator.
It extracts ( or takes ) the value from the keyboard and
assigns it to the variable on its right.
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Cascading of I/O Operators
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Multiple use of << or >> in one statement is called
cascading.
eg:cout << “Sum = ” << sum << “\n”;
cin >> number1 >> number2;
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Structure of a C++ Program
Include files
Class declaration
Member functions declaration
Main function program
Better to organize a program file into three separate files.
o
Class declarations in a header file.
o
Definition of member function in a separate file.
o
The main program that uses the class is placed in a third
file which includes the previous two files.
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