Object Oriented Programming lecture 1

CSC 103 - Object Oriented
Programming

Spring, 2011
Lecture 1, Background

14th Feb, 2011

Instructor: M. Anwar-ul-Haq

First Program
// my first program in C++

#include <iostream>
using namespace std;

int main ()
{
cout << “Hello World";
return 0;
}
OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
2

Background

• // comments
• Lines beginning with a hash sign (#) are
directives for the preprocessor.
• #include <iostream> tells the preprocessor
to include the iostream standard file.
• using namespace std; Elements of the
standard C++ library are declared within
what is called a namespace, the
namespace with the name std.
3

Background

• int main () The main function is the point
by where all C++ programs start their
execution, independently of its location
within the source code.
• For that same reason, it is essential that
all C++ programs have a main function.

4

Background

• cout << "Hello World!";
• cout is the name of the standard output
stream in C++, and the meaning of the
entire statement is to insert a sequence of
characters (in this case the Hello
World sequence of characters) into the
standard output stream (cout, which
usually corresponds to the screen).

5

Background

• cout is declared in the iostream standard
file within the std namespace, so that's
why we needed to include that specific file
and to declare that we were going to use
this specific namespace earlier in our
code.

6

Background

• This operator >> applied to an input
stream (cin) is known as extraction
operator.
• The << operator applied to an output
stream (cout) is known as insertion
operator.

7

C++ Structures
• A collection of one or more variables,
typically of different types, grouped
together under a single name for
convenient handling

• Known as struct in C and C++

8

C++ Structures
• Structures
– Aggregate data types built using elements of other
types
struct Time{ Structure tag

int hour;
Structure members
int minute;
int second;
};
– Members of the same structure must have unique
names
– Two different structures may contain members of the
same name
– Each structure definition must end with a semicolon
9

C++ Structures
• struct
– Creates a new data type that is used to
declare variables
– Structure variables are declared like variables
of other types

10

C++ Structures
• Member access operators:
– Dot operator (.) for structures and objects
– Arrow operator (->) for pointers
– Print member hour of timeObject:
cout << timeObject.hour;

11

Examples
struct point { struct { struct point {
int x; int x; int x;
int y; int y; int y;
}; } p1, p2; } p1, p2;

struct point p1, p2; p1 and p2 both same as the other
have the defined two versions, but
p1 and p2 are both structure, containing united into one set
points, containing an an x and a y, but of code, p1 and p2
x and a y value do not have a tag have the tag point

For the first and last sets of code, point is a defined tag and can be used
later (to define more points, or to declare a type of parameter, etc) but in
the middle code, there is no tag, so there is no way to reference more
examples of this structure
12

#include <iostream>

Example
#include <string>
//using std::string;
using namespace std;

struct employee{

int id_number;
int age;
string name;
float salary;
};

int main()
{
employee emp;

emp.id_number=1;
emp.age = 25;
emp.name="adsdfsd";
emp.salary =60000;

cout<<"Employee id:"<<emp.id_number<<endl;
cout<<"Employee Age:"<<emp.age<<endl;
cout<<"Employee Name:"<<emp.name<<endl;
cout<<"Employee Salary:"<<emp.salary<<endl;

return 0;
} OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
13

Object Oriented Programming lecture 1

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