Download Data Structures - Data structure cs322

Data Structures
1- Course Syllabus.
2- Introduction about Data Structures.
First: what is data structures?
Data Structures
A
data
structure
is
an
arrangement of data in a
computer’s
memory
(or
sometimes on a disk).
 Examples of data structures
include linked lists, stacks,
binary trees, and hash tables,
among others.
 Also, it is a object oriented
programming

Data Structures
Data Types
Hashes
Linear data
Trees
Primitive
Arrays
Binary trees
Composite
Lists
B-trees
Abstract
data type
Graphs
Heap Trees
AVL Trees
Multi way
trees
Space Trees
Application specific trees
Are Data structures important ???

Data structures are very useful
in the construction of a program
or a system, especially if the
program has to manage huge
amounts of data efficiently, such
as large databases, airline
system , students enrollment
system and others.

It
explains
the
way
of
organizing data or elements in a
computer memory
Algorithms

Algorithms manipulate the data in
these structures in various ways,
such as inserting a new data item,
searching for a particular item, or
sorting the items.

You can think of an algorithm as a
recipe: a list of detailed
instructions for carrying out an
activity.
Abstract Data Type (ADT)

Before a program is written we should have a fairy
good idea of how to accomplish the task being
implemented by this program.

It is important to specify each task in terms of input
and output.

Behavior of the program is more important than the
gears of the mechanism accomplishing it.

Ex. If an item needed in to accomplish some tasks,
the item is specified in terms of operations
performed on it rather than in terms of its inner
structure.
 ADT

These operations may act upon this item, for
example:
◦ Modifying it, searching for some details in it, or
sorting something in it.

After these operations are specified, the
implementation of the program may start.

The implementation decides which data
structure should be used to make execution
most efficient in terms of time and space.

ADT

An item specified in terms of operations is called an abstract data type.

Abstract Data Type (ADT): is a set of items and fundamental operations on
this set.

Abstraction? Anything that hides details & provides only the essentials.
◦ Examples: an integer 165 = 1.102+6.101+5.100, procedures/subprograms,
etc.

Abstract Data Types (ADTs) are Simple or structured data types whose
implementation details are hidden…

An abstract data type is not a part of a program, because a program written in
a programing language requires the definition of a data structure, not only the
operations on data structure.

An object oriented language( OOL) such as C++ has direct link to abstract
data types by implementing them as a class.

ADT: Example
ADT String1
Operations: Assume that there is a string S.
1.Procedure Append (c: char)
Requires: length(S) < 80.
Results: c is appended to the right end of S.
2. Procedure Remove (c: char)
Requires: length(S) > 0.
Results: The rightmost character of S is removed and
placed in c, S’s length decreases by 1.
3. Procedure MakeEmpty ()
Results: all characters are removed.
4. Procedure Concatenate (R: String)
Results: String R is concatenated to the right of string S,
result placed into S.
5. Procedure Reverse ()
6. Procedure Length (L: int)
7. Procedure Equal (S: String, flag: boolean)
8. Procedure GetChar (int i)
In C++ the class construct is used to
declare new data types.
 In C++ operations are implemented as
function members of classes or methods.

ADT String
class String1 {
private:
char[] str;
int
size;
puplic:
String1 () {
size = -1;
str = new char[80];
}
~String1(){}
void Append (char c) {
size++;
str[size] = c;
}
Representation
Implementation
 ADT
String
char Remove (){
char c = str[size];
size--;
return(c);
}
char GetChar(int i){
return(str[i]);
}
void MakeEmpty (){
size = -1;
}
int Length (){
return(size); }
void Concatenate (String1 s){
for (int i = 0; i<=s.Length(); i++) {
char c = s.GetChar(i);
Append(c);
}
}
boolean Equal (String1 s){
}
void Reverse () {
}
}

An abstract data type is not a part of a
program, because a program written in a
programing language requires the
definition of a data structure, not only the
operations on data structure.

An object oriented language( OOL) such
as C++ has direct link to abstract data
types by implementing them as a class.
Arrays