lecture3-4 chapt2

7/31/2019 lecture3-4 chapt2

1/76

2-1

Parts of a C++ Program

// sample C++ program#include using namespace std;

int main(){

cout


2/76

2-2

Special Characters

Character Name Meaning// Double slash Beginning of a comment

# Pound sign Beginning of preprocessordirective

< > Open/close brackets Enclose filename in #include

( ) Open/closeparentheses

Used when naming afunction

{ } Open/close brace Encloses a group of

statements" " Open/close

quotation marksEncloses string ofcharacters

; Semicolon End of a programmingstatement


3/76

Copyright 2009 Pearson Education, Inc. Publishing as Pearson Addison-Wesley

The cout Object2.2


4/76

2-4

The cout Object

Displays output on the computer screen

You use the stream insertion operator


5/76

2-5

The cout Object

Can be used to send more than one itemto cout:

cout


6/76

2-6

The cout Object

This produces one line of output:

cout


7/76

2-7

The endl Manipulator

You can use the endl manipulator to starta new line of output. This will produce two

lines of output:

cout


8/76

2-8


Programming isfun!

cout


9/76

2-9


You do NOT put quotation marks aroundendl

The last character in endl is a lowercaseL, not the number 1.

endl

This is a lowercase L


10/76

2-10

The \n Escape Sequence

You can also use the \n escapesequence to start a new line of output.

This will produce two lines of output:

cout


11/76

2-11

The \n Escape Sequence

Programming isfun!

cout


12/76


The #include Directive2.3


13/76

2-13

The #include Directive

Inserts the contents of another file into theprogram

This is a preprocessor directive, not part ofC++ language

#include lines not seen by compiler

Do not place a semicolon at end of#include line


14/76


Variables and Literals2.4


15/76

2-15

Variables

Variable: a storage location in memory

Has a name (identifier) and a type of data itcan hold

Must be defined (declared) before it can beused:

int item;


16/76

2-16

Variable Definition


17/76

2-17

#include using namespace std;

int main(){

int x;int y;y = 13;x = 25-y;cout


18/76

2-18

Literals

Literal: a value that is written into aprograms code.

"hello, there" (string literal)12 (integer literal)


19/76

2-19

20 is an integer literal


20/76

2-20

This is a string literal


21/76

2-21

This is also a string literal


22/76


Identifiers2.5


23/76

2-23

Identifiers

An identifier is a programmer-definedname for some part of a program:variables, functions, etc.

int main(){

int x;

int y;y = 13;x = 25-y;cout


24/76

2-24

C++ Key Words

You cannot use any of the C++ key words as anidentifier. These words have reserved meaning.


25/76

2-25

Variable Names

A variable name should represent thepurpose of the variable. For example:

itemsOrdered

The purpose of this variable is to hold thenumber of items ordered.


26/76

2-26

Identifier Rules

The first character of an identifier must be analphabetic character or and underscore ( _ ),

After the first character you may use alphabeticcharacters, numbers, or underscore characters. Upper- and lowercase characters are distinct


27/76

2-27

Valid and Invalid Identifiers

IDENTIFIER VALID? REASON IF INVALID

totalSales Yes

total_Sales Yes

total.Sales No Cannot contain .

4thQtrSales No Cannot begin with digit

totalSale$ No Cannot contain $


28/76


Integer Data Types2.6


29/76

2-29

Integer Data Types

Integer variables can hold whole numbers suchas 12, 7, and -99.


30/76

2-30

Defining Variables

Variables of the same type can be defined- On separate lines:

int length;int width;

unsigned int area;- On the same line:

int length, width;unsigned int area;

Variables of different types must be in differentdefinitions


31/76

2-31

This program has three variables:checking, miles, and days


32/76

2-32

Integer Literals

An integer literal is an integer value thatis typed into a programs code. For

example:

itemsOrdered = 15;

In this code, 15 is an integer literal.


33/76

2-33

Integer Literals


34/76


The char Data Type2.7

Th h D T


35/76

2-35

The char Data Type

Used to hold characters or very smallinteger values

Usually 1 byte of memory Numeric value of character from the

character set is stored in memory:

CODE:char letter;letter = 'C';

MEMORY:letter

67


36/76

2-36

Character Literals

Character literals must be enclosed insingle quote marks. Example:

'A'


37/76

2-37


38/76

2-38

A series of characters in consecutive memorylocations:

"Hello" Stored with the null terminator,

\0, at the end:

Comprised of the characters between the " "

H e l l o \0


39/76

2-39

String datatype #include

concatenationInt main(){

string word = oh the stress ; string word2 = of it all; string word3 = word + word2; //concatenatecout


40/76

1-

Algorithm for Baking a cake:

1. preheat oven to 450

2. mash 2 sticks butter and 1 cup sugar together in abowl.

3. beat 3 eggs in another bowl4. add 1 tsp baking soda, cup cocoa to bowl 25. add bowl 2 to bowl 16. mix well7. pour contents into greased cake pan8. put cake pan in oven for 1 hour9. remove cake voila

There are other ways to write algorithms diagrams,

flowcharts


41/76

2-41

LabWrite a program that does the following:

1. Declare 3 ints, 2 chars and 3 strings. Givethem meaningful names.2. Assign a value to each.3. Multiply first 2 ints and assign the result to the

third int.4. Print the 3 rd int to the screen with a statement

saying what it is: int 1 x int 2 = followed byendl

5. Print out the two chars in the same cout

statement: here are my chars: 6. Concatenate first 2 strings and assign resultto string 3.

7. Print out string 3 with statement here are myconcatenated strings:


42/76


Floating-Point Data Types2.8



43/76

2-431-


1. preheat oven to 450

2. mash 2 sticks butter and 1 cup sugar together in alarge bowl.

3. beat 3 eggs in another large bowl4. add 1 tsp baking soda, cup cocoa to bowl 25. add bowl 2 to bowl 16. mix well7. pour contents into greased cake pan8. put cake pan in oven for 1 hour9. remove cake voila

There are other ways to write algorithms diagrams,

flowcharts

//C++ program to bake a cake NOT


44/76

2-441-

p g#include using namespace std;int main()

{Big_bowl bowl1, bowl2;BakingPan my_pan;Oven my_oven;bowl1 = 1_pound_butter + 1_cup_sugar;beat bowl1;bowl2 = eggs;beat bowl2;bowl2 = bowl2 + cocoa + baking_soda;bowl1 = bowl1 + bowl2;my_pan = bowl1;my_oven = my_panreturn 0;

}

l


45/76

2-45

Floating-Point Data Types

The floating-point data types are:floatdoublelong double

They can hold real numbers such as:12.45 -3.8

Stored in a form similar to scientific notation

All floating-point numbers are signed

Fl ti g P i t D t T


46/76

2-46

Floating-Point Data Types

Fl ti g i t Lit l


47/76

2-47

Floating-point Literals

Can be represented in Fixed point (decimal) notation:

31.4159 0.0000625

E notation:3.14159E1 6.25e-5

Are double by default

Can be forced to be float ( 3.14159f ) orlong double ( 0.0000625L )


48/76

2-48


49/76


The bool Data Type2.9

The bool Data Type


50/76

2-50

Represents values that are true or false bool variables are stored as small integers false is represented by 0, true by 1:

bool allDone = true;

bool finished = false;

The bool Data Type

allDone

1 0

finished


51/76

2-51


52/76


Determining the Size of a Data Type2.10

Determining the Size of a Data


53/76

2-53

Determining the Size of a DataType

The sizeof operator gives the size of any data type orvariable:double amount;

cout


54/76


Variable Assignments and Initialization2.11

Variable Assignments and


55/76

2-55

Variable Assignments andInitialization

An assignment statement uses the = operator to store a value in a variable.

item = 12;

This statement assigns the value 12 to theitem variable.

Assignment


56/76

2-56

Assignment

The variable receiving the value mustappear on the left side of the = operator.

This will NOT work:

// ERROR!12 = item;

Variable Initialization


57/76

2-57

Variable Initialization

To initialize a variable means to assign ita value when it is defined:

int length = 12;

Can initialize some or all variables:int length = 12, width = 5, area;


58/76

2-58


59/76


Scope2.12

Scope


60/76

2-60

Scope

The scope of a variable: the part of theprogram in which the variable can beaccessed

A variable cannot be used before it isdefined


61/76

2-61


62/76


Arithmetic Operators2.13

Arithmetic Operators


63/76

2-63

Arithmetic Operators

Used for performing numeric calculations C++ has unary, binary, and ternary

operators: unary (1 operand) -5 binary (2 operands) 13 - 7 ternary (3 operands) exp1 ? exp2 : exp3

Binary Arithmetic Operators


64/76

2-64

Binary Arithmetic Operators

SYMBOL OPERATION EXAMPLE VALUE OF ans

+ addition ans = 7 + 3; 10

- subtraction ans = 7 - 3; 4

* multiplication ans = 7 * 3; 21

/ division ans = 7 / 3; 2

% modulus ans = 7 % 3; 1


65/76

2-65

A Closer Look at the / Operator


66/76

2-66

p

/ (division) operator performs integerdivision if both operands are integers

cout


67/76

2-67

p

%(modulus) operator computes theremainder resulting from integer division

cout


68/76


Comments2.14

Comments


69/76

2-69

Comments

Used to document parts of the program Intended for persons reading the source

code of the program: Indicate the purpose of the program Describe the use of variables Explain complex sections of code

Are ignored by the compiler

Single-Line Comments


70/76

2-70

Single Line Comments

Begin with // through to the end of line:int length = 12; // length in inches

int width = 15; // width in inchesint area; // calculated area

// calculate rectangle areaarea = length * width;

Multi-Line Comments


71/76

2-71

Multi Line Comments

Begin with /* , end with */ Can span multiple lines:

/* this is a multi-linecomment

*/ Can begin and end on the same line:

int area; /* calculated area */


72/76


Programming Style2.15

Programming Style


73/76

2-73

g g y

The visual organization of the sourcecode

Includes the use of spaces, tabs, andblank lines

Does not affect the syntax of the program Affects the readability of the source code

Programming Style


74/76

2-74

g g y

Common elements to improve readability: Braces { } aligned vertically Indentation of statements within a set of braces Blank lines between declaration and other

statements Long statements wrapped over multiple lines

with aligned operators

#include #i l d < t i >


75/76

2-75

#include using namespace std;

int main(){

int x = 10;int y = 15;cout


76/76

Program 1 Calculate area of a room. Declare 3 float variables, assign valuesto width and length of room. Assign area of room to third float.

Print that number to the screen with a statement the area of theroom is put an endl at the end.

Program 2 Concatenate 2 strings and determine the size of all three. Declare3 strings. Give values to the first two and assign theirconcatenated value to the third string. Print the concatenatedstring to the screen followed by endl, then print the size of that 3rdstring in memory. Try getting the size by using the word stringrather than the variable name.

Program 3 Declare 3 chars and 3 bool type variables. Give them values.Print the values to the screen. Try assigning values to bool of 1 or0, true or false, t and f. See what happens.

Program 4

lecture3-4 chapt2

Documents

Transcript of lecture3-4 chapt2