Computer Science 201 _csc 201

7/28/2019 Computer Science 201 _csc 201

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Compare Primitive to

Reference Data Types

Primitive data types can

perform simple arithmetic.

Reference data types require

methods to be manipulated.

Components (Specifications)

of a Problem

Initial conditions => Problem

=> Result

input => Plan of Action =>

Outcome

Control Structure

A group of individual instructions

in a program that takes control of

the program. The control structure

should have only one entry and one

exit point.

Define Algorithm as it Relates

to Computer Programs

An algorithm is a

programming recipe.

Define Algorithm as it Relates

to Problem Theory

Algorithms can be defined as

a refinement of a plan of

action.


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Define Real and Artificial

Formal Problems

Real - The making of a

product

Artificial - Simulated problem

(playing games/AI).

Demonstrate two ways to

declare the string msg = "foo"

String msg = new String

("foo"); //with instantiation

String msg = "foo"; //without

instantiation

Describe a left-decision tree

nested control structure

In a left-decision tree nested control structure the "IF"s are nested

in the "IF" structures not in the else block structure. They are not

commonly used. The syntax is as follows:

IF (cond1)

IF (cond2)

Statement 1

ELSE

Statement 2

ELSE

Statement 3

Describe a nested control

structure. What are the two

form of nestes control

structure

Multiple number of "IF" statements

are nested during a process. There

are two forms of nested control

structure, left-decision tree and

right-decision tree

Describe a one way selection

control structure

The conditional path is selected if

the condition is true. If false, the

corresponding statement(s) will be

passed and the lines of code

following the block are executed.


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Describe a right-decision tree

nested control structure

In a right-decision tree nested control structure, the statements are tested

until a true statement is found. This is the most common nested control

structure. The syntax follows:

IF (cond1)

Statement 1

ELSE

IF (cond2)

Statement 2

ELSE

IF (cond3)

Statement 3

ELSE

Statement 4

Describe a Switch Control

Structure

The switch statement allows you to choose from a

fixed set of alternatives. It is used in a narrow

collection of situations.

Switches should not be used with real numbers.

only Integers and integer compatibles (characters)

Switches must use "breaks" to avoid code "fall

through"

Describe a two-way selection

control structure

Regardless of conditions, one

of two paths will always be

taken

Describe Encapsulation

The mechanism that binds together codes

and data and prevents unauthorized

acces to the heart of the class which is

private. A class is designed such that the

implementation is protected from the

action of external code except through

form interface.

Describe Inheritance

Each object is related to one or

more objects. One class of objects

inherits data behavior from another

object. In other words, sub classes

share characteristics of the class

they are derived from.


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Describe Multi-way Selection

Control

Selection control that

involves more than two

structures.

Describe Polymorphism

The capability of an object to assume different

forms. Messages can lead to different operations

depending on the object receiving it. Example:

Context based right clicking

Formal definition: The mechanism by which one

general interface can be used to access different

specific implementations.

Describe the AND operator.

Give an example of how it can

be used with bit sequences

True when all conditions are true. The java syntax

is &&. Used for filtering/masking a bit pattern.

Allow only the 1st and 2nd bits through:

10101101

00000011

00000001

Describe the Bottom Up

design structure and give

advantages and

disadvantages

Modules are designed first, then put

together to form the main program.

Advantages: Less expensive and

faster to build

Disadvantages: The pieces don't

always work well together.

Describe the NOT operator.The NOT operator is used to

reverse a condition. Java

Syntax is !.


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Describe the OR operator.


be used with bit sequences

True when any input is true. The java

syntax is ||

Used for bit setting (sets any or all bits to

1) in a sequence.

Set the 2nd bit: 10101101

00000010

10101111

Describe the XOR operator.


be used with bit sequencing

Also ca lled the equivalence operator. Returns FALSE when both

statements are the same. The Java syntax is a compound statemen

(!ab + a!b). Used for testing bit sequence errors (unexpected state

change) and also for flipping:

10101101

11111111

01010010

Describe Top Down design

structure and give

advantages and

disadvantages

The overall structure of the program is

already known and modules are

integrated as design progresses.

Disadvantage: Expensive and time

consuming

Advantage: Highly customized.

Fields of Computer Science

Switching Theory

Software Engineering

Automation and Control

Robotics

Biotechnology

Hardware Design

Give a General Definition of

Algorithm

Algorithm is a set of defined

instructions which result into

a solution


6/16

How are Problems of

Analysis and Synthesis

Linked

Generally speaking software

engineers convert problems of

analysis to problems of

synthesis which can then be

solved by computers.

How does Java handle

dangling pointers caused by

string literals declared

without instantiation?

Java periodically runs a

GarbageCollection method to

eliminate objects with zero

reference.

Identifier vs Method Syntax Identifier - xyz

Method - xyz()

List the Logical Operators

OR NOR

XOR XNOR

AND NAND

NOT

Relational Operators

An operator which determines the

relationship of a one value to

another and returns a true or false

result. They are binary operators

!= >= < ==


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Selection Control Structure

Allows the program to execute one

of the alternative paths. The

selection is governed by the

outcome of a conditional test that

evaluates if a statement is true or

false.

Six Recommendations on the

Selection of Algorithms

1. Avoid algorithms which cause informal problems.

2. Avoid algorithms with undetermined solutions

3. Avoid algorithms which require excessive amounts

of time.

4. Select algorithms that closely fit the specifications

5. Select algorithms which allow for assumptions

6. Select algorithms which don't generate multiple

problems

6.1 Examine the algorithm's efficiency

String Tokenization

Using ReadLine(), it is possible to

convert a string of multiple items

into individual values (tokens).

String Tokenization generally

requires wrapper classes to convert

between different integer types

Suggestions for Program

Appearance

1. Format the program in a way that

enhances its readability

2. Use spaces between segments

3. All composite sequences must be

separated

4. Use appropriate (and well named)

identifiers

The Four Stages of

Programming Development

1. Program Planning

2. Program Coding

3. Testing and Debugging

4. Maintenance/Refactoring


8/16

Three Common Principles of

Programming Style

1. Program structure and

design

2. Program Documentation

3. Program Overall

Appearance and Style

What are conditions for a

Switch Control Structure?

1. When a comparison (equality) is

performed

2. When the same expression is being

compared in each condition

3. When the type of value to which the

expression being compared is integer

compatible

What are Formal Problems

Characterized by complete

specification of a problem:

initial conditions, plan of

action, and expected

outcome.

What are Informal Problems

Informal problems have no satisfactory

solution. The result of the problem

cannot be achieved knowing the

specifications of the problem (initial

conditions and the plan of action). There

is no satisfactory solution.

What are Logical Operators

Used for in Programming

1. For Supporting multiple or

complex conditions

2. For setting or clearing bit

sequences


9/16

What are Object Oriented

Programs

Complex software programs

requiring proper abstraction

and separating the internal

implementation from external

behavior of the object.

What are the elements of

program Documentation?

1. Explanation of components

2. Functioning of each unit

3. Summary of the problem specification

4. Special algorithms (if used)

5. Assumptions made

6. Formulation

7. Name of program

8. Date

9. Date of last modification

10. Project Name

11. Division/Dpt

12. References used for program development

What are the Four Stage of

Program Design?

1. Input Phase

2. Output Phase

3. Formulation of

Assumptions

4. Constraints

What are the three primary

characteristics of Objects in

OOP

Polymorphism

Inheritance

Encapsulation

What are the three types of

selection control structures?

One-way selection control

structure, two-way selection

control structure, and multi-

way selection control

structure.


10/16

What are the Two Categories

of Formal Problems

Problems of analysis and

problems of synthesis

What are the two forms of

multi-way selection control

Nested selection control and

switch control structure

What are the two method

types found in Java?

Strict (Instance) methods

Static methods

What are the two program

design structures that are

commonly used?

Top Down and Bottom Up

What are the two types of

control structures

Selection Control Structure

and Loop Control Structure


11/16

What are Wrapper Classes

Wrapper classes allow us to

convert between different

variable types: strings,

integers, doubles, booleans,

etc

What happens when a

Primitive Data Type is

declared?

1. A space is reserved for an int

data type

2. The variable name gets

associated with the first byte

of allocated storage

What happens when a

Reference Data Type is

declared?

1. A list of all variable objects and their associated

data types are generated for compiling.

2. Sufficient memory is allocated for the declared

type as referenced by the address.

3. The first byte of the address is assigned to the

reference name, only after the object is instantiated.

The allocation is not done until the object is

instantiated. Therefore string msg; does nothing.

What is a class in OOP?Consists of a Data Structure and

methods that can be applied to that

structure. A class is a module unit.

Class = operations + data structure

What is a Computer

Program?

A computer program is the statement of

an algorithm in a computer

programming language. It is a collection

of instructions that a computer can

understand, process and accomplish. It is

an exacting task.


12/16

What is a method in OOP?

A unit of a program module

that contains a sequence of

operations and statements. In

Java, methods can ONLY exist

within a class.

What is a module in OOP?

A structure consisting of

interrelated segments arranged in

logical order to form an integrated

unit. It is constructed basically from

classes.

What is a Plan of Action

A general outline of the major

steps we need to accomplish

our goal, starting at

predefined initial conditions.

What is a Problem of Analysis

A formal problem where the initial

condition (input) and the result (output)

are known. The goal is to identify the plan

of action.

Problems of Analysis are generally solved

by a programmer or software engineer

What is a Problem of

Synthesis

A formal problem where the initial

condition (input) and the plan of action

are known. The goal is to identify the

result (output).

Problems of Synthesis are generally

solved by a computer.


13/16

What is a Problem?

A goal or a task. The

difference between actual

conditions and those that are

required or desired.

What is a Shift operator

Used to shift bit patterns to the

right or to the left.

Logical shifts multiply or divide the

pattern by the pattern's base.

(LogicalShiftLeft x)

(LogicalShiftRight /)

What is a Static method in

Java?

Static methods are called by

prefixing them with the class name.

No instance variables of any object

of the class are defined in the

method. Example: Math.pow(2,3)

calls the exponent method pow.

What is a Strict method in

Java?

The method is associated with an object

and use the instance variables of that

object. Instance methods are called by

prefixing it with an object. Example:

System.out.println("")

Strict methods are also known as

instance methods

What is a String?

A string is a REFERENCE data type

where the variable references the

location in memory where the

actual value is stored. The actual

stored value is the object.


14/16

What is an abstract data

type?

Refers to a data type together

with a set of operations that

can be performed on that

data structure.

What is an Object

All objects have:

1. Name

2. Behavior

3. Receives input (receives message)

Example: Remote Control

name - remote control

behavior - changes channels on a television

receives input - from user using the number/keypad

What is Automatic

Dereferencing?

The process of obtaining the

address from a reference variable

and going to the address to retrieve

the correct number of bytes for the

object.

What is Computer Science?The study of how computers

can be applied effectively and

efficiently to solve problems.

What is InstantiationThe process of allocation that

creates a SPECIFIC instance

of an object


15/16

What is Parsing Parsing is the process of

tokenization

What is Problem Theory?

The study of characteristics of problems.

Most problems have certain

characteristics that are independent of

the details of any particular problem or

may have a relation to other problems in

general.

What is the input phase of

Program Design?

Identify where input comes

from and what they are.

User? Storage?

What is the output phase of

Program Design?

Identify the outputs of the

computer program. Does

something get displayed on

the screen? On a printer?

What is the Purpose of Object

Oriented Programming

To provide software developers with:

Reliability

Cost effectiveness

Adaptability

Understandability

Reusable


16/16

What kind of method is

Decimalformat("format

string")

DecimalFormat is a static

method because it is called

simply from it's class name.

No object name is used.

What two reference data

types don't require

instantiation?

Strings and arrays

Documents

Computer Science 201 _csc 201