C++ - Chapter 2 - C++ Programming Basics

8/18/2019 C++ - Chapter 2 - C++ Programming Basics

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OBJECT-ORIENTED

PROGRAMMING IN C++

Ahmed Mohamed Sayed AhmedComputer lecturer

Cisco Certified Academy Instructor


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Contents

Chapter Content

Chapter 1 The Big Picture

Chapter 2 C++ Programming Basics

Chapter 3 Loops and Decisions

Chapter 4 Structures

Chapter 5 Functions

Chapter 6 Objects and Classes

Chapter 7 Arrays and StringsChapter 8 Operator Overloading

Chapter 9 Inheritance

Chapter 10 Pointers

Chapter 11 Virtual Functions and Polymorphism

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Ahmed Mohamed Sayed Ahmed - Com uter lecturer Thursday, November 22, 2012


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The Chapter Contents

1. Getting Started

2. Basic Program Construction

3. Output Using cout

4. Directives

5. Comments

6. Integer Variables

7. Character Variables

8. Input with cin

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Chapter 2: C++ Programming Basics

9. Floating Point Types

10.Type bool

11.The setw Manipulator

12.Variable Type Summary

13.Type Conversion

14.Arithmetic Operators

15.Library Functions


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1. Getting Started

We will use a compiler from Visual Studio 6.0 program.

We can download the Visual Studio 6.0 program, for free,from these links:

http://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.html

(Free Register required)

https://rapidshare.com/files/3614028324/Visual%20Studio%206.0.zip

(Register not required)

Open the program by choose:

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http://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttps://rapidshare.com/files/3614028324/Visual%20Studio%206.0.ziphttps://rapidshare.com/files/3614028324/Visual%20Studio%206.0.ziphttps://rapidshare.com/files/3614028324/Visual%20Studio%206.0.ziphttps://rapidshare.com/files/3614028324/Visual%20Studio%206.0.ziphttps://rapidshare.com/files/3614028324/Visual%20Studio%206.0.ziphttps://rapidshare.com/files/3614028324/Visual%20Studio%206.0.ziphttps://rapidshare.com/files/3614028324/Visual%20Studio%206.0.ziphttps://rapidshare.com/files/3614028324/Visual%20Studio%206.0.ziphttps://rapidshare.com/files/3614028324/Visual%20Studio%206.0.ziphttps://rapidshare.com/files/3614028324/Visual%20Studio%206.0.ziphttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.htmlhttp://www.4shared.com/zip/jxr5H2F-/Visual_Studio_60.html


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1. Getting Started5



The Program Interface:


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1. Getting Started

Open new Project by choose: File New

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1


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1. Getting Started

From Projects tab, choose “Win32 Console Application”.

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1. Getting Started

In Project name box, write a name for your project, for example“My Project”. Then press OK button.

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1. Getting Started

Press on Finish button to continue…

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1. Getting Started

Press on OK button to finish creating the project.

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1. Getting Started

Open new File by choose: File New

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1. Getting Started

From Files tab, choose “C++ Source File”.

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1. Getting Started13



In File name box, write a name for your source code file, for example“FIRST”. Then press OK button.

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1. Getting Started

The compiler is ready now to write your source code.

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Compilers take source code and transform it intoexecutable files, which your computer can run as it doesother programs.

Source files are text files (extension .CPP) that we willlearn how to write it through our course.

Executable files have the .EXE extension, and can beexecuted either from within your compiler, or directlyalone.

A DSW file contains the text of a program beingdeveloped in the Microsoft C++ language. You will usethe file with DSW (Microsoft Developer StudioWorkspace) extension to open the project you created.


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Write the following code that will simply prints a

sentence on the screen.

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#include

using namespace std;int main( ){

cout


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There are two steps to complete building our first

project:

1. Press F7, or from Build menu choose Build FIRST.exe tofind out errors in our code.

2. Press Ctrl+F5, or from Build menu choose ExecuteFIRST.exe to build and execute our project.

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main function

The parentheses following the word main are the

distinguishing feature of a function. Without the

parentheses the compiler would think that main refers toa variable.

We’ll put parentheses following the function name. Later

on we’ll see that the parentheses aren’t always empty.

They’re used to hold function arguments: values passed

from the calling program to the function.

The word int preceding the function name indicates that

this particular function has a return value of type int.


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Braces and the Function Body

The body of a function is surrounded by braces.

These braces play the same role as the BEGIN and ENDkeywords in some other languages: They surround or delimit

a block of program statements.Always start with main ( )

When you run a C++ program, the first statement executedwill be at the beginning of a function called main ( ).

The program may consist of many functions, classes, andother program elements, but on startup, control always goesto main ( ).

If there is no function called main ( ) in your program, anerror will be reported when you run the program.


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Program Statements

A semicolon signals the end of the statement. If youleave out the semicolon, the compiler will often(although not always) signal an error.

The last statement in the function body is return 0; . Thistells main ( ) to return the value 0 to whoever called it,in this case the operating system or compiler.

In older versions of C++ you could give main ( ) the

return type of void and dispense with the return statement, but this is not considered correct in StandardC++.

You can put several statements on one line, separatedby any number of spaces or tabs.


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2. Basic Program Construction21



#includeusing namespace std;int main( ){ cout


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As you have seen, the statement:

causes the phrase in quotation

marks to be displayed on thescreen.

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cout


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As you have seen, the endl in statement:

causes the next text output to be displayed on a new line.

We use it here so that the phrases such as “Press any key tocontinue …” , inserted by some compilers for display after

the program terminates, will appear on a new line.

We can use another way to display the same output:

or

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cout


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4. Directives

The two lines that begin the FIRST program are directives.

The first is a preprocessor directive, and the second is a usingdirective. They’re not part of the basic C++ language, but

they’re necessary anyway.

The preprocessor directive #include tells the compiler to insert

another file into your source file. In effect, the #include directive is replaced by the contents of the file indicated.

The type file usually included by #include is called a header

file.

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#includeusing namespace std;


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4. Directives

In the FIRST example, the preprocessor directive #include

tells the compiler to add the source file iostream to the

FIRST.CPP source file before compiling. iostream is an example of a header file. It’s concerned

with basic input/output operations, and contains

declarations that are needed by the cout identifier and

the


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4. Directives

The using directive says that all the program statements

that follow are within the std namespace.

If we didn’t use the using directive, we would need to addthe std name to many program elements. For example:

To avoid adding std:: dozens of times in programs we use

the using directive instead.

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using namespace std;

std::cout


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5. Comments27



Comments are an important part of any program. Theyhelp the person writing a program, and anyone else who

must read the source file, understand what’s going on.

The compiler ignores comments, so they do not add to thefile size or execution time of the executable program.

A comment can start at the beginning of the line or on the

same line following a program statement.

We can write the comments using any languages we caneasily understand it.


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5. Comments

The first comment style start with a double slash symbol // and terminate at the end of the line.

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// comments.cpp

// demonstrates comments#include //preprocessor directiveusing namespace std; //”using” directive int main( ) //function name “main” { //start function body

cout


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5. Comments

There’s a second comment style available in C++. This

type of comment (the only comment originally available in

C) begins with the /* character pair and ends with */ (not

with the end of the line).

This is a good approach to making a comment out of a

large text passage, since it saves inserting the // symbol

on every line.

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/* this is an old-style comment */

/* this is a

potentiallyvery longmultilinecomment

*/


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5. Comments

You can also insert a /* …. */ comment anywhere withinthe text of a program line:

If you attempt to use the // style comment in this case, the

closing brace won’t be visible to the compiler. Since a //

style comment runs to the end of the line, and the code

won’t compile correctly.

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func1( )

{ /* empty function body */ }

func1( ){ // empty function body }

√

х


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Variables are the most fundamental part of any language. A variable has a symbolic name and can be given a

variety of values.

Variables are located in particular places in thecomputer’s memory.

When a variable is given a value, that value is actuallyplaced in the memory space assigned to the variable.

Most popular languages use the same general variabletypes, such as integers, floating-point numbers, andcharacters, so you are probably already familiar with theideas behind them.

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Variable Names

You can use uppercase and lowercase letters, and the digits

from 1 to 9. You can also use the underscore ( _ ).

The first character must be a letter or underscore. The compiler distinguishes between uppercase and

lowercase letters, so Var is not the same as var or VAR.

You can’t use a C++ keyword as a variable name. A

keyword is a predefined word with a special meaning. int,

class, if , and while are examples of keywords.

A variable’s name should make clear to anyone reading the

listing the variable’s purpose and how it is used.

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Integer variables represent integer numbers like 1, 30,000, and – 27. Such numbers are used for counting discrete numbers ofobjects, like 11 pencils or 100 students.

Unlike floating-point numbers, integers have no fractional part.

Integer variables exist in several sizes, but the most commonlyused is type int. The amount of memory occupied by the integertypes is system dependent. On a 32-bit system such as Windows,an int occupies 4 bytes (byte = 8 bits) of memory. This allows anint to hold numbers in the range from – 2,147,483,648 to2,147,483,647.

Type int occupies only 2 bytes in 16-bit systems such as MS-DOSand earlier versions of Windows.

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There are several numerical integer types besides type int.The two most common types are long and short. We noted

that the size of type int is system dependent. In contrast,

types long and short have fixed sizes no matter what system

is used.

Type long always occupies four bytes. Thus it has range,

from – 2,147,483,648 to 2,147,483,647.

Type short always occupies two bytes. Thus it has range,from – 32,768 to 32,767.

If you want to create a constant of type long, use the letter L

following the numerical value, as in:

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long var = 7678L;


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6. Integer Variables35



#includeusing namespace std;int main( ){

int var1; //define var1int var2; //define var2var1 = 20; //assign value to var1var2 = var1 + 10; //assign value to var2

cout


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The statement, ,is called declaration.

You must declare a variable before using it.

However, you can place variable declarations anywhere in

a program. It’s not necessary to declare variables before the first

executable statement (as was necessary in C).

However, it’s probably more readable if commonly-used

variables are located at the beginning of the program.

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int var1;


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Output Variations

The statement displays a string constant.

The next statement displays the value of

the variable var2. The output of the program is

As you can see, the output of the two cout statements

appears on the same line on the output screen. No linefeed

is inserted automatically. If you want to start on a new line,

you must insert a linefeed yourself.

or

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var1+10 is 30

cout


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7. Character Variables

Type char stores integers that range in value from – 128 to 127.Variables of this type occupy only 1 byte (eight bits) of memory.

Character variables are much more commonly used to store

ASCII characters.

The ASCII character set is a way of representing characters such

as ‘a’, ‘B’, ‘$’, ‘3’, and so on, as numbers.

Character constants use single quotation marks around a

character, like ‘a’ and ‘b’. (Note that this differs from string

constants, which use double quotation marks).

When the C++ compiler encounters such a character constant, it

translates it into the corresponding ASCII code. The constant ‘a’

appearing in a program, for example, will be translated into 97.

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ASCII Chart 39



ASCIIChart


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ASCII Chart 40




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ASCII Chart 41




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7. Character Variables42



// charvars.cpp: demonstrates character variables#include //for cout, etc.using namespace std;int main( ){

char ch1 = 'A'; //define char variable as character

char ch2 = '\t'; //define char variable as tab

cout


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Escape Sequence Character

\ n Newline

\ t Tab

\ ' Single quotation mark

\ " Double quotation marks

\ \ Backslash

\ xdd Hexadecimal notation

Escape Sequences

The character constant ‘ \ t’ is an example of an escape sequence.

The name reflects the fact that the backslash causes an “escape”

from the normal way characters are interpreted.


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Sometimes you need to represent a character constant thatdoesn’t appear on the keyboard, such as the graphics

characters above ASCII code 127.

To do this, you can use the ‘\xdd ’ representation, where each

d stands for a hexadecimal digit.

If you want to print a solid rectangle, for example, you’ll

find such a character listed as decimal number 178, which is

hexadecimal number B2 in the ASCII table. This characterwould be represented by the character constant ‘\xB2’ .


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8. Input with cin45



// fahren.cpp// demonstrates cin, newline#includeusing namespace std;int main( ){

int ftemp; //for temperature in fahrenheitcoutftemp;

int ctemp = (ftemp-32) * 5 / 9;cout


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8. Input with cin

The statement causes the program to wait forthe user to type in a number.

The resulting number is placed in the variable ftemp.

The keyword cin (pronounced “C in”) is an object,

predefined in C++ to correspond to the standard inputstream.

This stream represents data coming from the keyboard.

The >> is the extraction or get from operator. It takes thevalue from the stream object on its left and places it in thevariable on its right.

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cin>>ftemp;


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8. Input with cin

Expressions

Any arrangement of variables, constants, and operators that

specifies a computation is called an expression.

Thus, alpha+12 and (alpha-37)*beta/2 are expressions.

Precedence

Any Arithmetic operation proceeds according to an

established precedence of operations. Thus, Precedence is

the order in which operators are evaluated.

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Precedence Summary 48



#includeusing namespace std;int main( ){

int a=4, b=6, c=3, d, e, f, g;d = –a + b * c;e = (a + b) * c;f = a * b / c;g = a * (b / c);

cout


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Precedence Summary

The operators higher on the list have higher precedencethan those lower down.

Operators with higher precedence are evaluated before

those with lower precedence.

Operators on the same row have equal precedence.

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Floating-point variables represent numbers with a decimalplace like 3.1415927, 0.0000625, and – 10.2.

They have both an integer part, to the left of the decimal

point, and a fractional part, to the right.

Floating-point variables represent what mathematicians call

real numbers, which are used for measurable quantities such

as distance, area, and temperature. They typically have a

fractional part. There are three kinds of floating-point variables in C++:

type float, type double, and type long double.

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Type float

Type float stores numbers in the range of about 3.4x10 – 38

to 3.4x1038, with a precision of seven digits. It occupies 4

bytes in memory.

Type double

The larger floating point types, double, is similar to float

except that it requires more memory space and provide a

wider range of values and more precision. Type double requires 8 bytes of storage and handles

numbers in the range from 1.7x10 – 308 to 1.7x10308 with a

precision of 15 digits.

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9. Floating Point Types 52



//circarea.cpp//demonstrates floating point variables

#include //for cout, etc.using namespace std;int main( )

{float rad; //variable of type floatconst float PI = 3.14159F; //type const floatcoutrad; //get radius

float area = PI * rad * rad; //find areacout


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Exponential Notation You can write floating-point constants using exponential notation.

Exponential notation is a way of writing large numbers withouthaving to write out a lot of zeros.

For example, 1,000,000,000 can be written as 1.0E9 inexponential notation. Similarly, 1234.56 would be written1.23456E3. (This is the same as 1.23456 *103).

The number following the E is called the exponent. It indicateshow many places the decimal point must be moved to change thenumber to ordinary decimal notation.

The exponent can be positive or negative. The exponentialnumber 6.35239E – 5 is equivalent to 0.0000635239 in decimalnotation. This is the same as 6.35239 *10 – 5.

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The const Qualifier

The keyword const (for constant) precedes the data type of avariable. It specifies that the value of a variable will not change

throughout the program. Any attempt to alter the value of a variable defined with this

qualifier will elicit an error message from the compiler.

The #define Directive

The line appearing at the beginning of yourprogram specifies that the identifier PI will be replaced by thetext 3.14159 throughout the program.

However, you can’t specify the data type of the constant using

#define.

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const float PI = 3.14159F;

#define PI 3.14159


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10. Type bool

Variables of type bool can have only two possible values:true and false.

In theory a bool type requires only one bit (not byte) of

storage, but in practice compilers often store them as bytes

because a byte can be quickly accessed, while an individual

bit must be extracted from a byte, which requires additional

time.

As we’ll see, type bool is most commonly used to hold theresults of comparisons.

The true/false values are often called Boolean values.

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11. The setw Manipulator

You can think of each value displayed by cout as occupying afield: an imaginary box with a certain width.

The default field is just wide enough to hold the value. That is, the

integer 567 will occupy a field three characters wide, and the

string “pajamas” will occupy a field seven characters wide.

The setw manipulator causes the number (or string) that follows it

in the stream to be printed within a field n characters wide,

where n is the argument to setw( n ).

The declarations for the manipulators (except endl ) are not in the

usual iostream header file, but in a separate header file called

iomanip. When you use these manipulators you must #include this

header file in your program.

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11. The setw Manipulator 57



// width1.cpp// demonstrates need for setw manipulator

#includeusing namespace std;int main( )

{long sd1=83, sd2=78, sd3=91;cout


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// width1.cpp// demonstrates need for setw manipulator

#include#include // for setw using namespace std;

int main( ){

long sd1=83, sd2=78, sd3=91;cout


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#include#include // for setwusing namespace std;int main( ){



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#include#include // for setwusing namespace std;int main( ){



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12. Variable Type Summary61




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C++ - Chapter 2 - C++ Programming Basics