CS215 Lec 1   introduction
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File organization course: Introduction and history of File Management, and disk operations.

File organization course: Introduction and history of File Management, and disk operations.

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    CS215 Lec 1   introduction CS215 Lec 1 introduction Presentation Transcript

    • Grading and policy Course outline and references Object oriented concept revision String manipulation revision. Dr. Hussien M. Sharaf 2
    • Assignments and Projects: 22% Mid-Term Exam: 8% Lab: 10% Final Exam: 60% Dr. Hussien M. Sharaf 3
    • 1. Introduction to file management and OO Revision. 2. File organization and fundamental file/streams processing operations(opening, reading, writing, seeking). 3. Reading/writing fields of a single record. 4. List different methods for field organization. 5. Reading/writing records: using fixed length and variable length. 6. Reading/writing records: delimiters and simple Index. Buffering of records. Mid-Term exam (Lec 1- 5) Dr. Hussien M. Sharaf 4
    • 7. Linear/sequential and binary searching on files. 8. Reclaiming space in files (as a result for deletes and updates). 9. Key sorting and simple indexing. 10. Record operations with existence of Indexing. 11. Composite Indexing (primary and secondary indexes). 12. Multilevel indexing and introduction to B trees. 13. Using Hashing to locate records. Dr. Hussien M. Sharaf 5
    • Main Text book is Michael J. Folk, Bill Zoellick, Greg Riccardi; File Structures: An Object-oriented Approach with C++; Pearson Education These are other text books 1. Steve Teale; C++ IOStreams handbook; Addison-Wesley, 1993 2. D. S. Malik; Data Structures Using C++; Cengage Learning, Jul 31, 2009 Dr. Hussien M. Sharaf 6
    • A class is a data structure that holds data and functions. It can be seen as a container of related variables and functions. int x=500; char c=‘A’; string g; void incrementX(int x);function variables Dr. Hussien M. Sharaf 8
    • An object is an instantiation of a class. Class format: class class_name { access_specifier_1: member1; access_specifier_2: member2; ... } object_names; Where: class_name: is a valid identifier for the class. access_specifier: is one of the following three keywords: private, public or protected. members: can be data or function declarations. object_names: is an optional list of names for objects of this class. Variable definition int x; Class definition class class_name; Dr. Hussien M. Sharaf 9
    • Now let’s make a simple class for a rectangle. class Crectangle { public: int area (); int width, height; }; Crectangle class contains two data members (width, and height), and one public member function area that calculates area. Dr. Hussien M. Sharaf 10 int height; int width; int area(); Crectangle
    • Access specifiers modify the access rights that the members following them acquire. Private members: are accessible only from within other members of the same class. Public members: are accessible from anywhere where the object is visible. If none of the two words exist before any member of the class, then the default is private. Dr. Hussien M. Sharaf 11
    • The following figure shows the scope of each data member in different classes. Whole program class cl1{ private x; public y; }; private x; public y; int main() { ….. } class cl2{ private a; public b; }; private a; public b; Dr. Hussien M. Sharaf 12
    • A. Data members are variables declared inside the class definition. B. Methods: 1. Constructors initialize data members if needed. 2. set function stores the entered parameter into the corresponding data member. 3. get function returns the value of each data member, so each data member should have a get function that returns its value. Dr. Hussien M. Sharaf 13
    • Data members Constructor Get: within the class (like: area ()) Or Set: outside it (like: set_values (int,int)) #include <iostream> using namespace std; class CRectangle { int width, height; public: CRectangle(){width=1;} int area () {return (x*y);} void set_values (int,int); }; void CRectangle::set_values (int a, int b) { width = a; height = b; } Dr. Hussien M. Sharaf 14
    • #include <iostream> using namespace std; class CRectangle { //Declaration section public: int width, height; //Definition section int area () {return (width * height);} void set_values (int,int); }; void CRectangle::set_values (int a, int b) { width = a; height = b; } Output: rectangle’s area is: 20 int main () { CRectangle rect; rect.width = 4; rect.height = 5; //OR rect.set_values(4,5); cout << “rectangle’s area is: " << rect.area(); return 0; } Dr. Hussien M. Sharaf 15
    • Constructor is a special member function that must be defined with the same name as the class. Constructor is used to initialize data members of the class. Constructor only executed when a new object of the class is created. Constructors cannot return values. Constructors are declared public. Dr. Hussien M. Sharaf 16
    • Default constructor is a constructor with no parameters. It can be either: - Implicit: the compiler provides a default constructor, if no constructor has defined. It does not initialize the class’s data members, so they contain garbage data. - or Explicit: you define a constructor that takes no arguments, but from inside its body you have to initialize the data members of the class. Dr. Hussien M. Sharaf 17
    • #include <iostream> using namespace std; class CRectangle { int width, height; public: //Constructor without arguments CRectangle (){width=1;height=0;}; //Constructor with arguments CRectangle (int,int); int area () {return (width*height);} }; Dr. Hussien M. Sharaf 18 CRectangle:: CRectangle(int a, int b) { width = a; height = b; }
    • int main () { CRectangle rect_a(3,4); CRectangle rect_b(); rect_b.width=90; rect_b.height =80; cout << “rect_a width/height are: " << rect_a.width<<“/”<< rect_a.height<<endl; cout << “rect_b width/height are: " << rect_b.width<<“/”<< rect_b. height<<endl; cout << “rect_a area is: " << rect_a.area() <<endl; cout << “rect_b area is: " << rect_b.area() <<endl; system("Pause"); return 0; } Dr. Hussien M. Sharaf 19
    • You already use overloaded operators string s1( “Happy Term" ); cout<< “I wish you “<<s1; We need to write code to tell the compiler how to deal with any new class that we build. ofstream: Stream class to write on files ifstream: Stream class to read from files fstream: Stream class to both read and write from/to files. Dr. Hussien M. Sharaf 20
    • When overloading operators << and >> it is better to use ostream and istream which are the parents of ofstream and ifstream Dr. Hussien M. Sharaf 21 ostream istream iostream fstream ofstream cout ifstream cin
    • http://www.cplusplus.com/reference/iostream/
    • #include <iostream> using namespace std; class CRectangle { int width, height; public: //Constructor without arguments CRectangle (){width=1;height=0;}; //Constructor with arguments CRectangle (int,int); int area () {return (width*height);} //overload the in and out operators friend istream& operator >> (istream & stream, CRectangle & p); friend ostream& operator<<(ostream & stream, CRectangle & p); }; Dr. Hussien M. Sharaf 23 CRectangle::CRectangle(int a, int b) {width = a; height = b;} istream & operator >> (istream & stream, CRectangle & p) {stream>>p.width; stream.get(); // skip a char OR stream.ignore(); //skip a char stream>>p.height; return stream;} ostream & operator<<(ostream & stream, CRectangle & p) {stream<< p.width<<“,” << p.height<<endl; return stream;}
    • int main () { CRectangle rect_a(3,4); CRectangle rect_b; rect_b.width=90; rect_b.height =80; cout << “rect_a is: " << rect_a <<endl; cout << “rect_b is: " << rect_b<<endl; cout << “rect_a area is: " << rect_a.area() <<endl; cout << “rect_b area is: " << rect_b.area() <<endl; system("Pause"); return 0; } Dr. Hussien M. Sharaf 24
    • Dr. Hussien M. Sharaf 25
    • Below are some functions that are used to do different operations on strings. insert substringAppend(+)length replacefind String Manipulation Dr. Hussien M. Sharaf 26
    • Returns the length of the string. Example: string email = "d@h.com"; cout<<"Email length: "<<email.length()<<endl; Output: Email length: 7 Dr. Hussien M. Sharaf 27
    • Concatenates two chars/strings. We can use operator “+” to perform the append operation directly. Example: string myname = "Ahmed Yehia"; string job = ", Computer Engineer"; string mystr = myname + job; // Or mystr = myname.append(job); cout<< mystr <<endl; Output: Ahmed Yehia, Computer Engineer Dr. Hussien M. Sharaf 28
    • Inserts some additional content at a specific location within the string content. It takes two inputs: 1. Position from where to insert. 2. String to insert. Example: string myname = "Ahmed Yehia"; myname.insert(6, "M "); cout<< "My name is: " <<myname <<endl; Output: My name is: Ahmed M Yehia Dr. Hussien M. Sharaf 29
    • Searches the string for some specified content It takes two inputs (can take only the first): 1. The content to be matched. 2. Position from where to start search. It returns the position of the first occurrence in the string. Example: string myname = "Ahmed Yehia"; int pos1 = myname.find("e"); int pos2 = myname.find("e", 4); cout<< "first occurrence of e: " <<pos1<<endl; cout<< "second occurrence of e: " <<pos2<<endl; Output: first occurrence of e: 3 second occurrence of e: 7 Dr. Hussien M. Sharaf 30
    • substr results in a subset of the full string. It takes two inputs: 1. Position from where to start cutting the string. 2. Count of letters to extract. Example: string email = "d@h.com"; string domain = email.substr(2,email.length() -1); cout<<"Domain is: "<<domain<<endl; Output: Domain is: h.com Dr. Hussien M. Sharaf 31
    • Replaces a section of the current string by some other specified content. It takes three inputs: 1. Position from where to replace. 2. Count of letters to replace. 3. The replacement string. Example: string fname = "Ahmed Yehia"; fname.replace(6,5, "Ali"); cout<< "My friend’s name is: " <<fname <<endl; Output: My friend’s name is: Ahmed Ali Dr. Hussien M. Sharaf 32
    • #include <iostream> #include <string> using namespace std; int main () { string myname = "Hussien"; //append myname.append("Sharaf"); //insert myname.insert(7, " M "); cout<< "My name is: " <<myname <<endl; //length cout<< "My full name length is: " <<myname.length() <<endl; //find int spos1 = myname.find("s"); int spos2 = myname.find("s", spos1+1); cout<< "positions of s in " << myname << " are at: " << spos1<< ", " <<spos2 <<endl; //substr int space_pos = myname.find(' '); string firstName = myname.substr(0,space_pos); cout<<"My first name is: " <<firstName<<endl; //replace firstName.replace(4,2,"ei"); cout<<"My first name can be written as: "<<firstName<<endl; system ("pause"); return 0; } Dr. Hussien M. Sharaf 33
    • Dr. Hussien M. Sharaf 34
    • Run Example 1.3 using VS2008 or VS2010 Send the source code project (after zipping it) to my email: n.abdelhameed@fci-cu.edu.eg With subject: “FO – Assignment#1.3” Run Example 1.4 using VS2008 or VS2010 Send the source code project (after zipping it) to my email: n.abdelhameed@fci-cu.edu.eg With subject: “FO – Assignment#1.4” Dr. Hussien M. Sharaf 35
    • Next week is the deadline. No excuses. Don’t wait until last day. I can help you to the highest limit within the next 3 days. Dr. Hussien M. Sharaf 36
    • 1. Delete the debug folder. 2. Compress the solution folder using winrar. 3. Rename the compressed file as follows: StudentName_ID_A1.rar StudentName_ID_A2.rar 4. Email to: n.abdelhameed@fci-cu.edu.eg 5. Follow your marks at: http://tinyurl.com/p6qwdme Dr. Hussien M. Sharaf 37