cs116 senem kumova metİn. outline what is c++ ? some features of c++ input and output operations...

CS116 SENEM KUMOVA METİN

OutlineWhat is C++ ? Some features of C++Input and Output OperationsManipulatorsC++ header filesNamespaces and scope resolution operatorInline functionsReferences Default argumentsFunction overloadingFunction templates


What is C++?C++ is the work of Bjarne Stroustrup

of AT&T Bell Labs.

C++ is a mostly upward compatible extension of C that provides:

A better CSupport for Data AbstractionSupport for Object-Oriented ProgrammingC++ supports these paradigms; it does not

require their use


Some features of C++C++ is by far the most popular OOPL

Information Hiding (public & private)

Encapsulation (functionsmethods)

Abstract Data Types (stacks)

Inheritance (code reuse) vehicle car

truck bus

Polymorphism (having many forms)two_dim triangle ( area of triangle??)

square ( area of square??)


Input and Output Operations (1/6) Input to a program is treated as a stream

of consecutive bytes from keyboard , a disk file or some other source ..

Output is treated as a stream of consecutive bytes to video display, disk file or some other destination..

cin reads from standard input(keyboard)cout writes to standart output (screen)


Input and Output Operations (2/6)

#include <iostream> //header file without “.h” suffix

using namespace std;

main() {

cout << “Welcome to C++\n”;cout << “Welcome to C++"<< endl;

}


Input and Output Operations (3/6)#include <iostream> //header file without .h suffix


main() { cout <<“Welcome”<<“ to C++”<<endl; cout <<“Wel”<<“co”<<“me to “

<<“C++"<< endl;

cout <<“Did”<<endl<<“you” <<endl<<“understand?”<<endl;

} CS116 SENEM KUMOVA METİN

Input and Output Operations (4/6)#include <iostream> using namespace std;

int main() {

int value1, value2 = 0; cout << "enter integers: "; cin >> value1 >> value2;

cout <<"\nYou entered "<< value1 << “and” <<value2<< endl;

return 0; }


// A Simple Example

#include <iostream>using namespace std;

int main(){ int apples, oranges; // Declare two integer variables

apples = 5; oranges = 6; // Set initial values int fruit; // Declare a new variablefruit = apples + oranges; // Get the total fruit

cout << endl; // Start output on a new line

cout << “WE HAVE " << apples <<“ APPLES” <<endl;cout << “WE HAVE " << oranges << “ ORANGES“<<endl;cout << “WE HAVE " << fruit << “ FRUITS AT ALL…“<<endl;

return 0; // Exit the program}


// A Simple Example


int main(){ int apples, oranges; // Declare two integer variables

int fruit; // ...then another one

cin>>apples; // Get initial value from keyboardcin>>oranges; // Get initial value from keyboard fruit = apples + oranges; // Get the total fruit

cout << endl; // Start output on a new line

cout << “WE HAVE " << apples <<“ APPLES” <<endl;cout << “WE HAVE " << oranges << “ ORANGES“<<endl;cout << “WE HAVE " << fruit << “ FRUITS AT ALL…“<<endl;

return 0; // Exit the program}


Manipulators (1/4) Input and the output can be formatted by manipulators

Manipulators permanently change the state of the stream to which is applied (except setw)

For example placing “hex” in the output stream causes all subsequent output of ints, shorts, longs to be written in hexadecimal format

int a=19;cout<< a; // 19cout<<hex<<a; // 13

Manipulators without arguments require iostream file, manipulators with arguments require iomanip header file


Manipulators (2/4) endl write a newline

dec input or output in decimal oct input or output in octal hex input or output in

hexadecimal

fixed use fixed notation for floating point numbers: d.ddd

scientific use scientific notation for floating point numbers

left left justify right right justify

setfill(c) make c to fill character setprecision(n) set floating point precision to n setw(n) set field width to n


Needs iomanip header

file

Manipulators (3/4)#include<iostream>


main(){

int i=19;cout<< "i= "<< i <<" (decimal)\n";cout<< "i= "<< oct <<i <<" (octal)\n";cout<< "i= "<< hex<< i <<" (hexadecimal)\n";

cout<< "i= "<< i <<" (? ? ?)\n";cout<< "i= "<<dec<< i <<" (decimal)\n";

}


Manipulators (4/4)#include <iostream> #include <iomanip>


int main() {

int num1 = 12, num2 = 345, num3 = 6789;

cout << endl; //Start on a new line

cout << setw(6) << num1 << endl<< setw(6) << num2; cout << endl << setw(6) <<num3;

//Output three values

cout << endl; //Start on a new line return 0; //Exit program

}


C++ Header Files<iostream><iomanip><cmath><cstdlib><ctime><cstring><string> … (Chapter 15 p. 565-566 )


Namespaces & Scope Resolution Operator


main() {

cout << “Welcome to C++"<< endl;

}

#include <iostream>

main() {

std::cout << “Welcome to C++"<<std:: endl;

}


C++ provides namespaces to prevent name conflicts…Namespace std includes standard C++ definitions like cout, cin, endl

Namespaces & Scope Resolution Operator


namespace xxx { int flag; int s;}namespace yyy { int flag; int s;}

main(){ xxx::flag=3; // :: is the scope resolution operator yyy::flag=-1; }

// with a using declarationnamespace xxx { int flag; int s;}namespace yyy { int flag; int s;}

using xxx::flag;

main(){ flag=3; // xxx::flag=3; xxx:: s=0; yyy::flag=-1; yyy:: s=1; }

//using namespace declaration covers entire namespacenamespace xxx { int flag; int s;}namespace yyy { int flag; int s;}using namespace xxx;main(){ flag=3; s=0; // xxx::s=0; yyy::flag=-1; yyy:: s=1; cout<<flag; cout<< yyy::flag; }

Namespaces & Scope Resolution Operator// Declaring a namespace

#include <iostream>

namespace myStuff { int value = 0; }

int main() {

std::cout << "enter an integer: "; std::cin >> myStuff::value; std::cout << "\nYou entered " << myStuff::value << std::endl; return 0;

}


Namespaces & Scope Resolution Operator// Declaring a namespace

#include <iostream> namespace myStuff { int value = 0; } using namespace std;

int main() {

cout << "enter an integer: "; cin >> myStuff::value; cout << "\nYou entered " << myStuff::value << endl; return 0;

}


Inline functionPlacing the qualifier inline before function’s return type “advises” the compiler to generate a copy of the function’s in place to avoid a function call


Inline function



inline double cube(double side) {return side*side*side; }

main() { double sideValue;

cout << “enter the side lenght of the cube”<<endl;cin>>sideValue;

cout<< “Volume of the cube is ”<< cube(sideValue)<<endl;

}

ReferencesThere are two ways to call a function

Call by value (send the value of the variable)Call by reference (send the adress/reference of the

variable)

Call by reference in C pointersCall by reference in C++ pointers

references

int x a variableint & y a reference to a variable


CS116 SENEM KUMOVA METİN 23

ReferencesReference is signaled by & and provides an

alternative name for storage

int x;int & ref =x;x=3;ref=3;

x … ref

3

References



main() {

int x=2; int &y=x; // You have to initialize the references

cout<<x<<“ ” <<y<<endl;

x++;cout<<x<<“ ” <<y<<endl;

y++;cout<<x<<“ ” <<y<<endl;

References



int squareByValue (int);void squareByReference(int &);

main() { int x=2, y=4;

cout<<“before function call ”<<x<<endl;cout<<squareByValue(x)<<endl;cout<<“after function call ”<<x<<endl;

cout<<“before function call ”<<y<<endl;squareByReference(y);cout<<“after function call ”<<y<<endl; }

int squareByValue (int n) { n=n*n; return n;}

void squareByReference(int & n) {n=n*n; }


References : SWAP example#include<iostream>using namespace std;

void swap (int &, int &);

void main(){ int i=7 ; int j=-3;

swap (i,j);cout <<i<<endl;cout <<j<<endl; }

void swap (int & a, int & b){ int t= a;

a=b;b=t; }


Default ArgumentsC++ allows to specify default values for

function parameters….

void f (int v, float s=3.14, char t=‘\n’, string msg =“Error!!”);

Valid invocations:f(12, 3.5, ‘\t’, “OK”);f(12, 3.5, ‘\t’);f(12, 3.5);f(12);

Default Arguments



int boxVolume (int lenght=1, int height=1, int width=1);

main() {cout <<“Default volume”<< boxVolume()<<endl;cout<<“lenght=10,height=width=1”<<boxVolume(10)<<en

dl;cout

<<“lenght=10,height=20,width=1”<<boxVolume(10,20)<<endl;

cout <<“lenght=10,height=20,width=30”<<boxVolume(10,20,30)<<endl; }

int boxVolume (int lenght, int height, int width){return lenght*height*width;}


Function Overloading #include <iostream>using namespace std;

// C++ checks the number and type ofparameters to decide which overloaded function to use

int square( int a);int square( int a);

double square (double a);

int main(){ int x=8; double y=8;

cout<<square(x); cout<<square (y);return 0; }

int square(int a ){ return a*a; }

double square(double a){ return a*a; }


Function Overloading #include <iostream>#include <iomanip>using namespace std;

void print( int a);void print (double a);

int main(){ int x=8; double y=8;

print(x); print(y);return 0; }

void print (int a ){ cout <<a <<endl; }

void print (double a){ cout <<showpoint<< a <<endl; }

Function templates

template <class T>T GetMax (T a, T b) {if(a>b) return a;

else return b; }


char GetMax (char a, char b)

{ if(a>b) return a;else return b; }

float GetMax (float a, float b)

{ if(a>b) return a;else return b; }

int GetMax (int a, int b) { if(a>b) return a;

else return b; }

Function Template : Example 1#include <iostream> using namespace std;

template <typename T> T GetMax (T a, T b) { return (a>b?a:b); }

void main () { int i=5, j=6, k;

float l=10.0, m=5.3, n; k=GetMax(i,j); n=GetMax(l,m); cout << k << endl; cout << n << endl; }


Function Template : Example 2void printArray( const int *, int ); void printArray( const double *,

int ); void printArray( const char *, int );


template<class T>void printArray( const T *, int );

Function Template : Example 2#include <iostream>using namespace std;

template< typename T>void printArray( const T *array, int count ){ for ( int i = 0; i < count; i++ ) cout << array[ i ] << " ";

cout << endl; } // end function template printArray

void main(){ int a[ 5 ] = { 1, 2, 3, 4, 5 };

char b[ 4] = “C++";

cout << "Array a contains:" << endl;printArray( a, 5 );

cout << "Array b contains:" << endl; printArray( b, 4 ); }


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