3_C++ Programming.ppt

7/27/2019 3_C++ Programming.ppt

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C++ Programming

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Simple C++ Program

#include // include header file

using namespace std;

int main( )

{

cout


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What problem do namespaces solve?

Well, suppose that you buy two different general-purpose class libraries from two

different vendors, and each library has some features that you'd like to use.

You include the headers for each class library:

#include "vendor1.h"

#include "vendor2.h"

and then it turns out that the headers have this in them:

// vendor1.h

... various stuff ...

class String { ... };

// vendor2.h



This usage will trigger a compiler error, because class String is defined twice

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The namespace feature gets around this difficulty by means of separatenamed namespaces:

// vendor1.h


namespace Vendor1 {


}// vendor2.h


namespace Vendor2 {


}

There are no longer two classes named String, but instead there are nowclasses named Vendor1::String and Vendor2::String.

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How would you actually use the Str ing classes in these

namespaces?

Qualify the class name with the namespace name:

Vendor1::String s1, s2, s3;

This usage declares three strings, each of type Vendor1::String.

Another approach is to use a using directive:

using namespace Vendor1;

Such a directive specifies that the names in the namespace can be

used in the scope where the using directive occurs.

using namespace Vendor1; String s1, s2, s3; and pick up the String classfound in the Vendor1 namespace.

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Commonly used Header Files

< iostream > - Standard input and standard output functions

- Manupulating the time and date

< fstream > - Functions that perform input from files on disk and output to

files on disk

< cstdlib > - Conversion of text to numbers, numbers to text, randomnumbers and memory allocation

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Example 1

// Example - Display

#include


int main ( )

{

cout


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Example 2

/* ExampleDisplay * /

#include


int main ( )

{

cout


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Reading I nputs through Keyboard and F inding the Average

#include


int main( )

{

float number1, number2, sum, average;

cout > number1; // Reads numbers

cin >> number2; // from keyboard

sum = number1+number2;

average = sum/2;

cout


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Declaration ofvariables

// Operating wi th variables#include


int main ( )

{// declaring variables:

int a, b;

int result; // process:

a = 5;b = 2;

a = a + 1;

result = a - b;

// print out the result:cout


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Initialization ofvariables

// I ni tial ization of variables

#include


int main ( )

{int a=5; // initial value = 5

int b(2); // initial value = 2

int result; // initial value undetermined

a = a + 3;result = a - b;

cout


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Introduction to strings

// Str ing

#include

#include


int main ( )

{

string mystring = "This is a string";

cout


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Defined Constants

#include using namespace std;

#define PI 3.14159

#define NEWLINE '\n'

int main ( )

{

double r=5.0;

// radius double circle;

circle = 2 * PI * r;cout


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Compound Assignment

When we want to modify the value of a variable by performing anoperation on the value currently stored in that variable we can use

compound assignment operators:

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Expression Is equivalent to

value += increase; value = value + increase;

a - = 5; a = a - 5;

a / = 5; a = a / 5;

price *= unit+1; price = price * (unit+1);


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Compound Assignment Operator

// compound assignment operators

#include


int main ( )

{

int a, b=3;

a = b;

a+=2; // equivalent to a=a+2

cout


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I ncreaseand DecreaseOperator

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A++A += 1

A = A +1

A = 2

B = ++A

A = 3

B = 3

A = 2

B = A++

A = 3

B = 2

A = 2

B = --A

A = 1

B = 1

A = 2

B = A--

A = 1

B = 2

A--A -= 1

A = A -1


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Relational and Equality Operators

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= = Equal to!= Not equal to

> Greater than

< Less than

>= Greater than or equal to 4) // evaluates to true.(3 != 2) // evaluates to true.

(6 >= 6) // evaluates to true.

(5 < 5) // evaluates to false.


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Conditional Operators

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condition ? resul t1 : resul t2

7= =5 ? 4 : 3 // returns 3, since 7 is not equal to 5.

7= =5+2 ? 4 : 3 // returns 4, since 7 is equal to 5+2.

5 > 3 ? a : b // returns the value of a, since 5 is greater than 3.

a > b ? a : b // returns whichever is greater, a or b.


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Conditional Operators

// conditional operator

#include


int main ( )

{

int a, b, c;

a=2;

b=7;

c = (a>b) ? a : b;cout


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Expressions and Their Types

An expression is a combination of operators, constants and variables

arranged as per the rules of the language

It may also include function call which return values

Types of Expressions

Constant expressions

Integral expressions

Float expressions

Pointer expressions

Relational expressions

Logical expressions

Bitwise expressions

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Constant ExpressionsConsists of only constant values .

15, 20+5/2 x

I ntegral ExpressionsProduces integer results after implementing all the

automatic and explicit type conversions.

m, m*n-5 m+x

F loat ExpressionsProduce floating point result, after all conversions.

x+y 10.75 x+y/10

Pointer ExpressionsProduce address values.

&m ptr

(where m is a variable and ptr is a pointer)

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Relational Expressionsyield results of type bool which take a value true

or falsex b && x = = 10 x = = 10 || y = = 5

Bitwise Expressionsused to manipulate data at bit level

x > 1

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Special Assignment Expressions

Chained Assignment

x = ( y = 10 ); or x = y = 10;

Embedded Assignment

x = ( y = 50 ) + 10;

Compound Assignment

x += 10;

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Control Structures

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Control Structure

If-else

LoopSequenceSelection

switch do-while while, for


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Simple i fand if else statement

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if(x == 100)cout


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The whileloop

// custom countdown using while

#include


int main ( )

{

int n;

cout > n;

while (n > 0)

{

cout


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The do-whileloop

// number echoer

#include


int main ( )

{

unsigned long n;

do

{

cout > n;cout


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The forloop

// countdown using a for loop

#include


int main ( )

{for (int n=10; n > 0; n --)

{

cout


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The breakstatement// break loop example

#include

using namespace std;int main ( )

{

int n;

for (n=10; n>0; n--)

{

cout


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The continuestatement

// continue loop example

#include


int main ( )

{

for (int n=10; n>0; n--)

{

if (n= =5) continue;

cout


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The gotostatement

// goto loop example#include


int main ( )

{

int n=10;

loop:

cout


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The switchstatement

// Demonstrates switch statement

#include

int main( )

{

unsigned short int number;

cout > number;

switch (number)

{

case 0: cout


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Arrays

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Arrays

An array is a series of elements of the same type placed in contiguousmemory locations that can be individually referenced by adding an index to

a unique identifier.

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A typical declaration for an array in C++ is:

type name [elements];

int billy [5];


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Initializing Array Elements

int billy [5] = {16, 2, 77, 40, 12071}

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When an initialization of values is provided for an array, C++ allows the

possibility of leaving the square brackets empty [ ].

In this case, the compiler will assume a size for the array that matches the

number of values included between braces { }

int billy [ ] = {16, 2, 77, 40, 12071}


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Accessing the Values of an Array

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billy[2] = 75;

a= billy[2];

At this point it is important to be able to clearly distinguish between the

two uses that brackets [ ] have related to arrays.

They perform two different tasks: one is to specify the size of arrays when

they are declared; and the second one is to specify indices for concretearray elements.

** Do not confuse these two possible uses of brackets [ ] with arrays.

int billy[5]; // declaration of a new array

billy[2] = 75; // access to an element of the array.


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Array Example

#include using namespace std;

int billy [ ] = {16, 2, 77, 40, 12071};

int n, result=0;

int main ( )

{

for ( n=0 ; n


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Multidimensional Arrays

Multidimensional arrays can be described as "arrays of arrays"

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int jimmy [3][5];

jimmy [1][3]


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Multidimensional Array

#define WIDTH 5

#define HEIGHT 3

int jimmy [HEIGHT][WIDTH];

int n, m;

int main ( )

{

for (n=0; n


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Pointers

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Reference Operator (&) / Dereference operator (*)

andy = 25;

fred = andy;

ted = &andy;

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The variable that stores the reference to another variable is called as pointer

beth = *ted;


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PointersExample 1

#include


int main ( )

{

int firstvalue, secondvalue;

int * mypointer;

mypointer = &firstvalue;

*mypointer = 10;

mypointer = &secondvalue;

*mypointer = 20;

cout


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3_C++ Programming.ppt

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