giao trinh tin hoc chuong 1

8/14/2019 giao trinh tin hoc chuong 1

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2003 Prentice Hall, Inc. All rights reserved.

1Chapter 1 Introduction to C++

Programming

Outline

1. History of C and C++

2. C++ Standard Library

3. Basics of a Typical C++ Environment4. Introduction to C++ Programming

5. A Simple Program: Printing a Line of Text

6. Another Simple Program: Adding Two Integers

7. Arithmetic8. Decision Making: Equality and Relational Operators

9. Introduction to Object Technology


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2

History of C and C++

History of C

Evolved from two other programming languages

BCPL and B Typeless languages

Dennis Ritchie (Bell Laboratories)

Added data typing, other features

Development language of UNIX

Hardware independent

Portable programs

1989: ANSI standard

1990: ANSI and ISO standard published

ANSI/ISO 9899: 1990


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History of C and C++

History of C++

Extension of C

Early 1980s: Bjarne Stroustrup (Bell Laboratories) Spruces up C

Provides capabilities for object-oriented programming

Objects: reusable software components Model items in real world

Object-oriented programs

Easy to understand, correct and modify

Hybrid language

C-like style

Object-oriented style

Both


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4

C++ Standard Library

C++ programs

Built from pieces called classes and functions

C++ standard library Rich collections of existing classes and functions

Building block approach to creating programs

Software reuse


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5

Basics of a Typical C++ Environment

C++ systems

Program-development environment

Language C++ Standard Library


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6


Phases of C++ Programs:

1. Edit

2. Preprocess

3. Compile

4. Link

5. Load

6. Execute

Loader

PrimaryMemory

Program is created inthe editor and stored

on disk.

Preprocessor program

processes the code.

Loader puts program

in memory.

CPU takes each

instruction and

executes it, possibly

storing new data

values as the program

executes.

Compiler Compiler createsobject code and stores

it on disk.

Linker links the object

code with the libraries,

creates a.out and

stores it on disk

Editor

Preprocessor

Linker

CPU

Primary

Memory

.

.

.

.

.

.

.

.

.

.

.

.

Disk

Disk

Disk

Disk

Disk



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Input/output cin

Standard input stream Normally keyboard

cout

Standard output stream

Normally computer screen

cerr

Standard error stream

Display error messages



8

Introduction to C++ Programming

C++ language

Facilitates structured and disciplined approach to computer

program design Following several examples

Illustrate many important features of C++

Each analyzed one statement at a time

Structured programming

Object-oriented programming



9A Simple Program:

Printing a Line of Text

Comments

Document programs

Improve program readability Ignored by compiler

Single-line comment

Begin with // Preprocessor directives

Processed by preprocessor before compiling

Begin with #


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2003 Prentice Hall, Inc.

All rights reserved.

1 // Fig. 1.2: fig01_02.cpp

2 // A first program in C++.

3 #include

4

5 // function main begins program execution

6 int main()

7 {

8 std::cout



11A Simple Program:


Standard output stream object

std::cout

Connected to screen



121.21 A Simple Program:


Escape Sequence Description

\n Newline. Position the screen cursor to thebeginning of the next line.

\t Horizontal tab. Move the screen cursor to the nexttab stop.

\r Carriage return. Position the screen cursor to thebeginning of the current line; do not advance to the

next line.

\a Alert. Sound the system bell.

\\ Backslash. Used to print a backslash character.

\" Double quote. Used to print a double quotecharacter.


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1 // Fig. 1.5: fig01_05.cpp

2 // Printing multiple lines with a single//statement

3 #include

4


6 intmain()7 {

8 std::cout



14Another Simple Program:

Adding Two Integers

Variables

Location in memory where value can be stored

Common data types int - integer numbers

char - characters

double - floating point numbers

Declare variables with name and data type before use

int integer1;

int integer2;

int sum;

Can declare several variables of same type in one declaration

Comma-separated list

int integer1, integer2, sum;



15Another Simple Program:

Adding Two Integers

Input stream object >>(stream extraction operator)

Used with std::cin Waits for user to input value, then pressEnter(Return) key

Stores value in variable to right of operator

Converts value to variable data type

= (assignment operator)

Assigns value to variable

Binary operator (two operands)

Example:

sum = variable1 + variable2;


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1 // Fig. 1.6: fig01_06.cpp

2 // Addition program.

3 #include


6 int main()

7 {

8int integer1; // first number to be input by user

9 int integer2; // second number to be input by user

10 int sum; // variable in which sum will be stored

11 std::cout > integer1; // read an integer13 std::cout > integer2; // read an integer

15 sum = integer1 + integer2; // assign result to sum

16 std::cout



17

Arithmetic

Arithmetic calculations *

Multiplication /

Division

Integer division truncates remainder

7 / 5 evaluates to 1

%

Modulus operator returns remainder

7 % 5 evaluates to 2



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Arithmetic

Rules of operator precedence Operators in parentheses evaluated first

Nested/embedded parentheses

Operators in innermost pair first Multiplication, division, modulus applied next

Operators applied from left to right

Addition, subtraction applied last Operators applied from left to right

Operator(s) Operation(s) Order of evaluation (precedence)

() Parentheses Evaluated first. If the parentheses are nested, the

expression in the innermost pair is evaluated first. Ifthere are several pairs of parentheses on the same level

(i.e., not nested), they are evaluated left to right.

*, /, or% Multiplication Division

Modulus

Evaluated second. If there are several, they re

evaluated left to right.

+

or

-

AdditionSubtraction Evaluated last. If there are several, they areevaluated left to right.



19Decision Making: Equality and Relational

Operators

if structure Make decision based on truth or falsity of condition

If condition met, body executed Else, body not executed

Equality and relational operators

Equality operators Same level of precedence

Relational operators

Same level of precedence Associate left to right




Operators

Standard a lgeb ra ic

eq uality opera tor or

rela tiona l opera tor

C++ eq ua lity

or re la tiona l

operator

Example

of C++

condition

Mea ning o f

C++ cond ition

Relational operators

> > x > y x is greater than y

< < x < y x is less than y

>= x >= y x is greater than or equal to y




Operators

using statements Eliminate use ofstd::prefix

Write cout instead ofstd::cout


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1 #include

2 using std::cout; // program uses cout

3 using std::cin; // program uses cin

4 using std::endl; // program uses endl


6 int main()

7 {8 int num1; // first number to be read from user

9 int num2; // second number to be read from user

10 cout num1 >> num2; // read two integers

13 if ( num1 == num2 )

14 cout


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17 if ( num1 < num2 )

18 cout


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Introduction to Object Technology

Object oriented programming (OOP) Model real-world objects with software counterparts

Attributes (state) - properties of objects

Size, shape, color, weight, etc.

Behaviors (operations) - actions

A ball rolls, bounces, inflates and deflates Objects can perform actions as well

Inheritance

New classes of objects absorb characteristics from existing classes

Objects

Encapsulate data and functions

Information hiding

Communicate across well-defined interfaces

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User-defined types (classes, components)

Data members

Data components of class

Member functions

Function components of class

Association

Reuse classes

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Object-oriented analysis and design (OOAD)

process Analysis of projects requirements

Design for satisfying requirements

Pseudocode Informal means of expressing program

Outline to guide code

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