CHAPTER 2 Intro to CPP Programming

8/22/2019 CHAPTER 2 Intro to CPP Programming

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OBJECTIVES:

At the end of the chapter the students should be able to:

1. Familiarize themselves with the Microsoft(MS) Visual

C++ Integrated Development Environment (IDE).2. Understand the basic components of a C++ program.

3. Classify identifiers, keywords, constants, and variables.

4. Enumerate and apply the basic data types of C++.

5. Identify the different operators to be used.

6. Know the precedence of operators.

CHAPTER 2INTRODUCTION TO

C++ PROGRAMMING


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C++ was developed mainly for an object-oriented programming (OOP) approach.

However, it can process both OOP and structured programming, with the latter being the

focus of this books discussions.

2.1The Integrated Development Environment (IDE)

Before we get our hands dirty, it would be better for us to navigate the editor that we will

be using in programming C++.

Figure 2.1

The Microsoft Visual C++ IDE

Figure 2.1 illustrates the C++ editor, commonly called the Integrated Development

Environment or IDE. An IDE is a program that hosts the compiler, debugger, and

application-building tools. You can create programs, access the online help, and performdebugging without leaving the IDE. Below are some of the common features of the MS

Visual C++ IDE:

TitleBar MenuBar ToolBar

Wiz

ard

Bar

Project

Workspace

Editor Window

Output Window

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Automatic syntax highlighting colors keywords, comments, and other source

code in different colors.

Automatic smart indenting helps line up your code into easy-to-read columns.

Auto-Completion automatically displays a menu of items to help you finish C++

statements.

Parameter Help displays the parameters for Windows functions as you type.

Integrated keyword help enables you to get help on any keyword just by pressing

F1.

Drag-and-drop editing enables you to move text easily by dragging it with the

mouse.

Integration with the compilers error output helps you step through the list of

errors reported by the compiler and positions the cursor at every error.

Like any other Windows application, the MS Visual C++ Environment has its own titlebar, menu bar, and toolbars to help users perform programming tasks fast and easy. It

also has three separate windows which perform different functions: documentoreditor,

project workspace, and output.

The Document Window / Editor Area

The area on the right side of the IDE is the editor area. This is the area where youperform all your editing when using MS Visual C++.

The Project Workspace Window

The workspace, as it is normally called, appears on the left side of the IDE. It allows you

to navigate the various parts of your development code, and can be viewed in two

different ways:

1. The Class View,which allows you to navigate and manipulate your source code

on a C++ class level;and

2. The File View,which allows you to view and navigate all the files that make up

your application.

The Output Window

The output window appears at the bottom of the IDE and remains open until you chooseto close it. It provides information such as compiler progress statements, warnings, and

error messages.

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2.2 A Simple C++ Program

Let us look at a very simple example of a C++ program:

Source Code 2.1

Welcome to C++!!!

Source Code 2.1 is what is referred to as a program source code. It is made up of a

combination of letters, numbers and other symbols. We will be writing and executing

programs using the MS Visual C++ IDE.

In this book, we will write C++ programs using the following format:

void main(void){

}

HEADER FILES

Like other programming languages, C++ has a large collection of pre-defined functions.

You may think of a function as a group or sequence of statements. In some cases,

programmers refer to functions as subprograms. The word pre-defined means thatusers or programmers can use the function without knowing or concerning themselves

how they were written. For the meantime, we will only be using the header file

iostream.h, which stores the standard input/output functions of C++.

FUNCTIONS

/* This is a simple C++ program */

/* declaration of header file */

#include

/* start of main program */

void main(void)

{

cout


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All statements should be written inside a user-defined function. The word user-defined

means that it is the user who defined (or wrote) the description of a function. In Source

Code 2.1, there is only one user-defined function the main() function. Take note that allC++ programs must have a main() function.

STATEMENTS

All C++ programs are made up of a sequence of instructions. In C++, instructions are

also called statements, wherein a semicolon terminates each statement.

In Source Code 2.1 above, there is only one statement -- the coutstatement. coutis thestandard output operator of C++ that is stored in the header file iostream.h.

THE { } SYMBOLS

The symbols { (open brace or open curly bracket) and } (close brace or close curly

bracket) are used for grouping purposes. In the example program above, the open and

close curly brackets signify the beginning and the end of the main() function respectively.

Take note however that the curly brackets must always come in pair. A missing curly

bracket is one of the most common causes ofsyntax errors. A syntax error is a

programming error violating the rules that specify how a command or instruction should

be written.

As we shall see later on, the curly brackets are used to group several statements.

THE /* */ SYMBOLS

The symbols /* and */ are used for block comments inside the program. Comments

simply provide additional information such as what the program is doing: what are the

inputs, what are the outputs, etc. Think of /* as the beginning of a comment, and the */ as

the end a comment. Just like the curly brackets, they symbols always come in pair.

Comments are optional and maybe placed anywhere within the program source code.

It is possible to write several lines of comments inside /* */. For example:

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Source Code 2.2

Block Comment

Note that comments cannot be nested, i.e. you cannot put /* */ inside /* */. For example,

the following will cause a syntax error:

/*

this is a comment

/* this is one more comment which will cause an error */

*/

Another option that can be used in inserting comments is by using // (double slash) for

single line comments. This is so because the comment terminates at the end of the

current line. For example:

Source Code 2.3

Single Line Comment

#include

/* The following is

an example

of a very simple C program */

void main(void)

{

cout


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2.3 Identifiers, Keywords, Constants, and Variables

2.3.1 NAMING CONVENTIONS

Data and instructions to manipulate data are referred to by their names, also called

identifiers. In C++, the following are rules and conventions to follow in giving a name:

1. Names are made up of letters and digits.

2. The first character must be a letter or an underscore (_). However, an underscore

is not recommended to be used as the first character in a name since some of C+

+s internal identifiers begin with underscores.3. C++ is case-sensitive, i.e., the lower-case letter a is not the same as the

uppercase letter A.

4. At least the first 31 characters of a name are significant.

Valid

Identifiers

Invalid Identifiers

Names Error Description

a 1 must start with a character

A 1_ab must start with a character

main a& & symbol cannot be used in a name

salary_per_day xyz_% % cannot be used in a name

Student_1

Student1

Table 2.1

Examples of Valid and Invalid Names in C++

Table 2.1 above shows some examples of valid and invalid names in C++.

2.3.2 KEYWORDS

MS Visual C++ has its own set of keywords. These names are reserved and cannot beused for other purposes such as in naming user-defined variable names. In the example

source codes above, the name void is a keyword. The MS Visual C++ language has a

total of 59 keywords shown below.

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break enum operator template

bool explicit private this

case extern protected throw

catch false public truechar float register try

class for reinterpret_cast typedef

const friend return typeid

const_cast goto short typename

continue if signed union

default inline sizeof unsigned

delete int static using

do long volatile virtual

double mutable static_cast void

dynamic_cast namespace struct while

else new switch

Table 2.2

C++ Keywords

It is important to note that main is a not a keyword in C++. However, although the name

coutis actually not a C++ keyword and is not really part of the language, it is a name pre-

defined in the standard input/output library, thus, it cannot be used as an identifier in C++

like main.

2.3.3 CONSTANTS

Constants are entities whose value does not change. A constant can either be numeric

constant or a literal constant. In C/C++, a numeric constant can be an integer or floating

point number, while a literal constant can be a single character or a string, i.e. a constant

with more than one character. A single character is written such that it is enclosed in a

pair of single quotes. A string is written enclosed in a pair of double quotes.

Numeric Constants Literal Constants

1 'A'

123 "A"

-123 "Welcome to C++!!!"

3.1416 "The quick brown fox jumps over the lazy dog."

Table 2.3Examples of C++ Constants

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The Table 2.3 shows some examples of numeric and literal constants. It is important to

note that even if 'A' and "A" contains the same value, they are of different types. The

former is a character while the latter is a string.

2.3.4 VARIABLES

A program is made of data and instructions to manipulate those data. Note that data have

to be stored somewhere, and thus will need some memory space in the Random AccessMemory (RAM). In a C++ program, a variable is the entity that holds data. A variable, as

the name suggests, is a varying entity depending on the actual data it holds. Without

variables, it would be impossible to store data. A variable has the following

characteristics:

1. a symbolic name;

2. an associated physical memory space (portion in a RAM);3. a data type;

4. a value that depends on the data type;

5. a scope; and

6. a lifetime

2.4 Basic Data Types in C++

A data type specifies the kind of values can be assumed by a variable of that type, the

range of values that can be assumed by a variable of that type, and the amount of memory

(in bytes) needed by a variable to store a value of that type.There are five basic data types in C++, namely:

char the character data type. The char data type is used to

represent/store/manipulate character data values. The range of values that can be

assumed by a char value is from 0 to 255. The number-to-character coding that isused in the American Standard Code for Information Interchange (ASCII).

int the integer data type. The int data type is used to represent/store/manipulate

signed whole numbers. The range of values that can be assumed by an int value

is from -2147483648 to 2147483647.

float the single precision floating point data type. The float data type is used to

store single precision signed real numbers. The appropriate range of values that

can be assumed by a float value is from 3.4 X 10 -38 to 3.4 X 1038. double the double precision floating point data type. The double data type is

used to store double precision signed real numbers. The appropriate range of

values that can be assumed by a double value is from 1.7 X 10-308 to 1.7 X 10308.

bool the Boolean data type. The bool data type is used to represent Boolean

values true orfalse.

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The amount of memory space required to store an int, a floatand double is platform-

dependent (depends on the machine and the software). For compilers such as the

Microsoft Visual C++ compiler, a charand boolrequires 1 byte of memory each, an int

andfloatrequires 4 bytes of memory each, while a double requires 8 bytes of memory.

Note that a chardata type is actually numeric (from 0 to 255), and is treated as a subset

ofintvalues. Any operation on integer values can also be performed on characters.

The following program can be used to print the sizes of the basic data types:

Source Code 2.4

ThesizeofOperator

Thesizeofis a keyword in C++. It is an operator that yields the size in number of bytes

of the specified data type.

2.5 Variable Declaration

A variable declaration is an action by which a variable is introduced to a

program/function. All variables in a C++ program must be declared. If you forgot to do

so, the compiler will report a syntax error. The syntax for declaring a variable is as

follows:

;

A semicolon signifies the end of a declaration. A missing semicolon will cause thecompiler to generate a syntax error. Variables should be named following the C++

naming conventions. For example:

#include

void main(void){

cout


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char ch;

bool b;

int i;

float f;double d;

It is possible to declare several variables of the same type on the same line. In such a

case, a comma should be inserted between two variables. A missing comma will generate

a syntax error. For example:

char ch1, ch2;

bool b1, b2;

int x, y, z;

float degree_celsius, degree_fahrenheit, degree_kelvin;

double numerator, denominator;

In general, C++ allows the user to declare variables in any part of the program code

before they can be used, but this is not advisable, especially for long programs.

Although we can use any name for the variables, it is recommended, however, as a good

programming practice for you to use a name that is descriptive or suggestive. For

example, if you know that a variable will represent a temperature in degree Celsius, then

dont use names such as x or c1. It is better to use a variable name such as celsius or

degree_celsius. Note that the use of the underscore makes reading the variable name easy

to read.

By default, the value of a variable in C++ is GARBAGE, i.e., there is something stored inthat memory space but that something is invalid for the intended use. The use of a

variable with a garbage value will cause a logical error. Unlike syntax errors, the

compiler is not capable of detecting logical errors since these are errors committed by theprogrammer on the program or logic flow. To avoid such instance, we must assign a

valid value to a variable before performing any operation on the variable.

2.6 Operators

Operators are symbols representing operations that can be performed on constants and

variables. There are four basic operations available in C++ language.

1. Assignment Operation

2. Arithmetic Operation

3. Relational Operation

4. Logical Operation

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The assignment operator is denoted by the equal symbol (=). It is used to store (i.e.,

assign) a value to a variable. The syntax of an assignment operation is:

= ;

In the syntax above, variable name can be any valid identifier in C++, while expression

can be a constant, variable or a valid expression.

2.6.1 THE ASSIGNMENT OPERATOR

The assignment operation is also a statement, thus a semicolon should terminate it.

Source Code 2.5 below shows how to use the assignment statement. Expect, however,

that if you run the program, there will be no output will be produced.

Source Code 2.5

The Use of the Assignment Statement

It is also possible to assign a value of a variable to another variable of a compatible data

type. For example:

ch1 = Z;

ch2 = ch1;

x = 5;

y = x;

/* a sample program demonstrating the use of assignment statement */void main(void)

{

// declaration of variables

char ch;bool b;

int i;

float f;

double d;

ch = A; // assign a char value to char variable

b = false; // assign a false value (0) to bool variable

i = 5; // assign an int value to int variablef = 1.25; // assign a float value to float variable

d = 3.14159; // assign a double value to double variable

}

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If in some cases we assign a value whose data type is different from the data type of the

receiving variable, the data type of the value will be converted to the data type of the

variable (either demoted or promoted).

2.6.2 THE ARITHMETIC OPERATORS

MS Visual C++ supports a number of operators. The basic arithmetic operations, plus

some other operations are available in C++ language. These are as follows:

OPERATOR DESCRIPTION

+ (plus) addition (returns the sum of two operands)

- (minus or dash) subtraction (returns the difference of two operands)

* (asterisk) multiplication (returns the product of two operands)

/ (slash) division (returns the quotient of two operands)% (percent) modulus operator (returns the remainder)

++ (double plus) increment (returns the value of an operand plus 1)

-- (double minus) decrement (returns the value of an operand minus 1)

TABLE 2.4

C++ Basic Arithmetic Operators

The +, -, *, / , ++, and (we will elaborate more on the ++ and operators later) can be

used for operands of type int, float and double data types. Actually, they can also be used

on char since char is a subset of int. The % operator can be used only with integer

operands. The first five operators in Table 2.4 are called binary operators because they

require two operands, while the increment and decrement operators are referred to asunary operators because they require only one operand.

The following program shows how to use the arithmetic operators with integer operands:

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Source Code 2.6

The Use of Arithmetic Operators

In the example above, the statement e = 18 / 8; will result into a 2 instead of 2.25 (i.e.,

the fractional part .25 is discarded). This is what we refer to as integer division, which

occurs when the operands of the division operator are both whole numbers: char or

integer values.

When one of the operands is a float or double, the division is a real number division. For

example:

18.0 / 8 will result into 2.25

C++ also provides a casting function which can be used to force a variable or an

expression to be of a specific data type. The syntax for type casting is as follows:

()

or

()

Thus, the following operations can be used to retain the fractional part .25 from the

previous example:

#include

void main(void){

int a, b, c, d;float e;

a = 10 + 15;

b = 27 - 13;c = 4 * 6;

d = 24 % 5;

e = 18 / 8;

cout


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(float)18 / 8

float(18) / 8

18 / float(8)

18 / (float)8

There are some important notes to remember in the use of C++ operators:

Assigning a variable to a constant is syntax error. For example:

12345 = x;

Assigning the value of a variable to a variable of the same name is syntactically

correct, but practically useless and does not make any sense. For example:

a = 12345;

a = a; // a get the value of a, which is 12345

It is usual in programming to assign a value of an expression to a variable,

wherein the old value of the variable is also used in the expression. For example:

a = 50;

a = a + 1;

The statement a = 50; means the value 50 is assigned to a. The next statement adds 1 to

this value resulting to 51, which is then assigned as the new value ofa.

When an expression has sequence of arithmetic operations, it is evaluated following the

MDAS rule, wherein multiplication or division should be performed first before additionor subtraction. To override this usual priority of operation, a pair of parentheses should

be used. For example, given the expression:

A + B * C

Here the multiplication operation will be performed first before the addition. To perform

the addition before multiplication, we have to write the arithmetic expression as:

( A + B ) * C

Earlier, we were presented a C++ statement a = a + 1; which simply means increment

the value of the variable a by 1. In the same way, if we intend to decrement a variable,say a, by 1 we can use the statement a = a - 1;. However, C++ provides a shortcutin

performing such operations: the unary operators ++ (double plus) and -- (double minus).

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The ++ is used to increment the value of an integer variable by 1. The -- is used to

decrement the value of an integer variable by one. Source Code 2.7 illustrates the use of

the ++ and operators.

Source Code 2.7The ++ and -- Operators

Used in a statement by themselves, the operators can be placed before or after a variable

yielding same results. On the other hand, using the operators in a more complex

expression will produce a different output. Source Code 2.8 shows an application of this

behavior.

#include

void main (void)

{

char ch1, ch2;

int a, b;

a = 2;

a++;

cout


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Source Code 2.8

The Use of the Prefix/Suffix ++ and -- Operators

In the sample program above, the output after the statement b = a++; yields

a = 11

b = 10

while the output after the statement b = ++a; yields

a = 11

b = 11

2.6.3 THE RELATIONAL/COMPARISON OPERATORS

The relational/comparison operators in C++ are as follows:

#include

void main (void){

int a, b;

a = 10;

b = a++; // suffix ++

cout


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== (double equal sign) equal to

!= (exclamation and equal sign) not equal to

> (greater than sign) greater than< (less than sign) less than

>= (greater than and equal sign) greater than or equal to

y);

d = (x < y);

e = (x >= y);f = (x


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2.6.4 THE LOGICAL OPERATORS

The logical operators in C++ are as follows:


! (exclamation mark) not

&& (double ampersand) and

|| (double bar) or

TABLE 2.6

C++ Basic Logical Operators

The logical operators are normally used in conjunction with relational operators to test

for multiple conditions. The logical NOT is a unary operator, it is used with only one

operand to its right. The remaining operators are binary operators. The logical NOToperation is performed before logical AND, before logical OR.

An actual C++ program that shows the result of the operators is presented below.

Source Code 2.9

The Use of Logical Operators

#include

void main(void)

{

/* logical NOT operator */cout


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2.6.5 THE PRECEDENCE OF OPERATORS

The precedence of operators depends on their priority and associativity (i.e. is the

expression evaluated from left to right or right to left). The table below presents the

precedence and associativity of operators from highest to lowest. Operators that appear

together have equal precedence and are evaluated according to their associativity.

OPERATOR ASSOCIATIVITY

( ) postfix++ postfix-- Left to right

! prefix++ prefix-- & sizeof Right to left

type casting Right to left

* / % Left to right

+ - Left to right

< >= Left to right== != Left to right

&& Left to right

|| Left to right

= *= /= %= += -= Right to left

Table 2.7

Precedence of Operators

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SUMMARY

In this chapter we described the basic components of the Microsoft Visual C++ integrated

development environment, which will be used in developing C++ programs. We also

looked at the basic components in constructing a C++ program. Identifiers, keywords,

constants, and variables were described. The basic data types of C++ were discussed

accompanied by some example programs.

Finally, the different operators accepted by the language were discussed including their

precedence.

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PRACTICE EXERCISE #2

NAME: __________________________ DATE: _______________________

COURSE/YR-SEC: ________________ INSTRUCTOR: _______________

A. DIRECTION: Write C++ programs that will declare variables (using the appropriate

data type) and assign values to these variables for the following problems. You can use

any constant value for initialization purposes.

1. Compute the sum of the integer values 1, 3, 5, 7, 8, and 9.

2. The area of a rectangle is computed as length multiplied by width.

3. The area of a triangle is computed as of the base multiplied by the height.

4. The circumference of the circle is computed as 2 multiplied by PI (a constant

value approximated as 3.1416) multiplied by the radius.5. The parameter of a square is computed as four multiplied by the length of its

side.

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NAME: __________________________ DATE: _______________________

COURSE/YR-SEC: ________________ INSTRUCTOR: _______________

B. DIRECTION: Determine the results of the following operations.

1. (A > B)

2. (5.0 7)

7. (2.0 < 2 || 5 > 5.0)

8. !(5 4 || !(1))))

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CHAPTER 2 Intro to CPP Programming

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