object oriented programming lecture 1
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CSC 103 - Object Oriented Programming
Spring, 2011
Lecture 1, Background
14th Feb, 2011
Instructor: M. Anwar-ul-Haq
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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First Program
// my first program in C++
#include <iostream> using namespace std;
int main () {
cout << “Hello World"; return 0;
}
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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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.
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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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.
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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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).
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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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.
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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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.
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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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++
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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C++ Structures• Structures
– Aggregate data types built using elements of other types struct Time{
int hour;
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
Structure tag
Structure members
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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C++ Structures
• struct – Creates a new data type that is used to
declare variables– Structure variables are declared like variables
of other types
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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C++ Structures
• Member access operators:– Dot operator (.) for structures and objects– Arrow operator (->) for pointers– Print member hour of timeObject:
cout << timeObject.hour;
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Examples
struct point { int x; int y; };
struct point p1, p2;
p1 and p2 are bothpoints, containing anx and a y value
struct { int x; int y;} p1, p2;
p1 and p2 bothhave the definedstructure, containingan x and a y, butdo not have a tag
struct point { int x; int y;} p1, p2;
same as the othertwo versions, butunited into one setof code, p1 and p2have the tag point
For the first and last sets of code, point is a defined tag and can be usedlater (to define more points, or to declare a type of parameter, etc) but inthe middle code, there is no tag, so there is no way to reference moreexamples of this structure
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OOP, Spring 2011, Engr. Anwar, Foundation University (FUIEMS), Islamabad
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Example#include <iostream>#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;}