Lecture 5 - Simple C++ Prog. Pt 1.pdf

8/14/2019 Lecture 5 - Simple C++ Prog. Pt 1.pdf

1/20

1992-2012 by Pearson Education, Inc. & John Wiley & SonsSome portions are adopted from C++ f or Everyone by Horstmann

ENGR 1200U Introduction to Programming

Lecture 5

Simple C++ Programs (Chapter 2)

Dr. Eyhab Al-Masri

ENGR 1200UWinter 2013 - UOIT

/*--------------------------------------------------------

* Program chapter1_1

* This program computes the distance between two points.

*/

#include // Required for cout, endl.

#include // Required for sqrt()

using namespace std;

int main()

{

// Declare and initialize objects.

double x1(1), y1(5), x2(4), y2(7),

side1, side2, distance;

// Compute sides of a right triangle.

side1 = x2 - x1;

side2 = y2 - y1;

distance = sqrt(side1*side1 + side2*side2);

// Print distance.

cout


2/20


/*--------------------------------------------------------



*/




int main()

{


double x1(1), y1(5), x2(4), y2(7),



side1 = x2 - x1;

side2 = y2 - y1;


// Print distance.

cout


3/20


/*--------------------------------------------------------



*/




int main()

{


double x1(1), y1(5), x2(4), y2(7),



side1 = x2 - x1;

side2 = y2 - y1;


// Print distance.

cout


4/20


/*--------------------------------------------------------



*/




int main()

{


double x1(1), y1(5), x2(4), y2(7),



side1 = x2 - x1;

side2 = y2 - y1;


// Print distance.

cout


5/20


/*--------------------------------------------------------



*/




int main()

{


double x1(1), y1(5), x2(4), y2(7),



side1 = x2 - x1;

side2 = y2 - y1;


// Print distance.

cout


6/20


/*--------------------------------------------------------



*/




int main()

{


double x1(1), y1(5), x2(4), y2(7),



side1 = x2 - x1 side2 = y2 - y1;


// Print distance.

cout


7/20


/*--------------------------------------------------------



*/




int main()

{


double x1(1), y1(5), x2(4), y2(7),



side1 = x2 - x1;

side2 = y2 - y1;


// Print distance.

cout


8/20


/*--------------------------------------------------------



*/




int main()

{


double x1(1), y1(5), x2(4), y2(7),



side1 = x2 - x1;

side2 = y2 / 0;


// Print distance.

cout


9/20


The characters \n are not printed on the screen

The backslash (\) is called an escape character. It indicates that a special character is to be output

The escape sequence \n means newline Causes the cursor to move to the beginning of the

next line on the screen

When the return statement is used at the end of main

the value 0 indicates that the program has terminatedsuccessfully



10/201


For each problemthe programmer goesthrough these steps

Algorithms No!An algorithm is

aRECIPE


Any solvable computing problem can be solvedby the execution of a series of actions in aspecific order

An algorithm is a procedure for solving aproblem in terms of

the actions to execute and

the order in which the actions execute

Specifying the order in which statements(actions) execute in a computer program iscalled program control


11/201


Pseudocode is an artificial and informal languagethat helps you develop algorithms. Similar to everyday English

Convenient and user friendly.

Helps you think out a program beforeattempting to write it.

Carefully prepared pseudocode can easily beconverted to a corresponding C++ program.


C++ Standard Library C++ programs consist of pieces called classes and

functions

Most C++ programmers take advantage of the richcollections of classes and functions in the C++ StandardLibrary

Two parts to learn the C++ world The C++ language itself, How to use the classes and functions in the C++

Standard Library


12/201


C++ systems consist of three parts: Program development environment Language C++ Standard Library

Typically, there are six phases in which C++programs go through Edit Preprocess Compile Link

Load, and Execute


Data type double is for specifying real numbers,and data type char for specifying character data.

Real numbers are numbers with decimal points,such as 3.4, 0.0 and 11.19

A char variable may hold only a singlelowercase letter, a single uppercase letter, asingle digit or a single special character (e.g., $

or *) Types such as int, double and char are called

fundamental data types


13/201


A number writtenby a programmer

is called anumber li teral.

There arerules for

writing literalvalues:


Keyword Example of a constant bool t r ue

char ' 5'

i nt 25

doubl e 25. 0

st r i ng "hel l o" //#i ncl ude

Fundamental Data Types contd)


14/201

1992-2012 by Pearson Education, Inc. & John Wiley & SonsSome portions are adopted from C++ f or Everyone by Horstmann

Constants and Variables


Constants and variables represent memory locations that are usedto store information

Constants are objects that store specific data that can not bemodified. 10 is an integer constant

4. 5 is a floating point constant

"The di st ance between the t wo poi nt s i s" is a string constant

'a' is a character constant

Variables are named memory locations that store values that canbe modified. doubl e x1( 1. 0) , x2( 4. 5) , si de1;

si de1 = x2 - x1;

x1, x2 and si de1 are examples of variables that can be modified.


15/201


Must begin with an alphabetic character or the

underscore character _

You cannot use other symbols such as $ or %. Spaces

are not permitted inside names;

Alphabetic characters may be either upper or lower case

C++ is CASE SENSITIVE, so a != A, etc May contain digits, but not as the first character

May NOT be C++ keywords



16/201


The following statement defines a variable.

intcans_per_pack= 6;

cans_per_packis the variables name.

int

indicates that the variable cans_per_pack

will be used to hold integers.

= 6

indicates that the variable cans_per_pack

will initially contain the value 6.



17/201


You should pick a variable name that explains itspurpose A good name describes the contents of the variable or

what the variable will be used for

For example, it is better to use a descriptive name,such as can_volume, than a terse name, such as cv.

Must be declared (and therefore typed) beforethey may be used

C++ is a strongly typed programming language Every variable must be declared before usage


When creating variables, the programmerspecifies the type of information to be stored(data type)

C++ does not provide initial values for variables Initialization is putting a value into a variable when it is

created

Initialization is not required

Using the value of a variable before it is initialized mayresult in garbage


18/201


Bits: smallest data item takes value of 0 or 1

Characters: decimal digits (0-9), letters (A-Z), and specialcharacters (i.e. $, %, @, #, &, *, (, ), , :,;,-,/)

Fields: Group of characters or bytes that convey meaning (i.e.persons name, car model, etc)

Records: Group of related fields

File: a group of related records (contains arbitrary data

and arbitrary format) Some OSs view files as sequence of bytes



19/201


Memory snapshots are diagrams that show thetypes and contents of variables at a particularpoint in time.



20/20


A type declaration statement defines new identifiers andallocates memory.

An initial value may be assigned to a memory location atthe time an identifier is defined.

Syntax[modifier] type specifier identifier [= initial value];[modifier] type specifier identifier[ initial value)];Examples

double x1, y1(0);int counter=0;const int MIN_SIZE=0;bool error(false);char comma(',');

Documents

Lecture 5 - Simple C++ Prog. Pt 1.pdf