A Complete Guide to Programming in C++ part 50 potx

ListEl* getNext const { return next; }friend class List; }; // Output an element ostream& operator... first = first->next; // Move to the next element... 4 7 7Dynamic Members This chapte

if( a3 == NULL)

cerr << "\n Invalid position!\n" << endl;

else

{

cout << " The new spliced array: " << endl;

for( i = 0; i < len3; ++i)

cout << setw(12) << a3[i];

cout << endl;

}

delete[] a1; delete[] a2; delete[] a3;

return 0;

}

// -// Function splice() inserts the array v2 into v1

// starting at position pos

int *splice( int v1[], int len1,

int v2[], int len2, int pos) {

if( pos < 0 || pos > len1)

return NULL;

int i = 0, i1 = 0, i2 = 0;

int *v = new int[len1+len2];

for( i = 0, i1 = 0; i1 < pos; ++i, ++i1) // 1st part

v[i] = v1[i1];

for( i2 = 0; i2 < len2; ++i, ++i2) // 2nd part

v[i] = v2[i2];

for( ; i1 < len1; ++i, ++i1) // 3rd part

v[i] = v1[i1];

return v;

}

Exercise 2

// -// merge.cpp

// Implements the merge algorithm

//

-#include <iostream>

#include <iomanip>

#include <cstdlib>

#include <ctime>

using namespace std;

// Prototypes:

void selectionSort( int arr[], int len);

int *merge( int v1[], int len1, int v2[], int len2);

int main() {

cout << "\n * * * The Merge Algorithm * * *\n"

<< endl;

int i, len1 = 10, len2 = 20;

int *a1 = new int[len1],

*a2 = new int[len2];

// Initialize the random number generator // with the current time:

srand( (unsigned)time(NULL));

for( i=0; i < len1; ++i) // Initialized arrays: a1[i] = rand();

for( i=0; i < len2; ++i) a2[i] = rand();

selectionSort( a1, len1); // To sort array a1 selectionSort( a2, len2); // To sort array a2 // Output the arrays:

cout << "The sorted arrays:" << endl;

cout << "1st array: " << endl;

for( i = 0; i < len1; ++i) cout << setw(12) << a1[i];

cout << endl;

cout << "2nd array: " << endl;

for( i = 0; i < len2; ++i) cout << setw(12) << a2[i];

cout << endl;

int *a3, len3;

a3 = merge( a1, len1, a2, len2);

len3 = len1 + len2;

cout << setw(12) << a3[i];

cout << endl;

delete[] a1; delete[] a2; delete[] a3;

return 0;

}

//

-// Function selectionSort()

inline void swap( int& a, int& b) // To swap

{ int temp = a; a = b; b = temp; }

void selectionSort( int *arr, int len)

{

register int *p, *minp; // Pointer to array elements, int *last = arr + len-1; // Pointer to the last element for( ; arr < last; ++arr)

{

minp = arr; // Search minimum

for( p = arr+1; p <= last; ++p) // starting at

if( *minp > *p) // position arr

minp = p;

swap( *arr, *minp); // To swap

}

}

//

-// merge() : Merges two sorted arrays to create

// a new sorted array

int *merge( int v1[], int len1, int v2[], int len2)

{

int i = 0, i1 = 0, i2 = 0;

int *v = new int[len1+len2]; // New int array

for( i=0; i1 < len1 && i2 < len2; ++i)

{

if( v1[i1] <= v2[i2])

v[i] = v1[i1++];

else

v[i] = v2[i2++];

}

if( i1 < len1) // Copy the rest of v1 or v2

while( i1 < len1)

v[i++] = v1[i1++];

else

while( i2 < len2)

v[i++] = v2[i2++];

return v;

}

Exercise 3

// -// date.h : Defines the class Date

// -// date.cpp

// Implements the methods of class Date, // which are not inline defined

// -//

// These files are left unchanged // from Chapter 14 (solutions)

//

// -// List.h

// Defines the classes ListEl and List // to represent a linked list

//

-#ifndef _LIST_H_

#define _LIST_H_

#include "Date.h"

#include <iostream>

#include <iomanip>

using namespace std;

class ListEl {

private:

Date date; // Date double amount; // Amount of money ListEl* next; // Pointer to successor

public:

ListEl( Date d = Date(1,1,1),

double b = 0.0, ListEl* p = NULL) : date(d), amount(b), next(p) {}

// Access methods const Date& getDate() const { return date; } void setDate() // Sets the current date {

date.setDate();

} bool setDate( int day, int month, int year) {

return setDate( day, month, year);

}

ListEl* getNext() const { return next; }

friend class List;

};

// Output an element

ostream& operator<<( ostream& os, const ListEl& le);

//

-// Defines the List class

class List

{

private:

ListEl* first, *last;

public:

List(){ first = last = NULL; } // Constructor

~List(); // Destructor

// Access first and last elements:

ListEl* front() const { return first; }

ListEl* back() const { return last; }

// Appends a new element at the end of the list:

void pushBack(const Date& d, double b);

// Deletes an element at the beginning of the list

void popFront();

};

// Outputs the list

ostream& operator<<( ostream& os, const List& le);

#endif // _LIST_H_

//

-// List.cpp

// Implements the methods of class List,

// which are not previously defined inline

//

-#include "List.h"

// Destructor of the list:

List::~List()

{

ListEl *pEl = first, *next = NULL;

for( ; pEl != NULL; pEl = next)

{

next = pEl->next;

delete pEl;

}

}

// Appends a new element at the end of the list:

void List::pushBack(const Date& d, double b) {

ListEl *pEl = new ListEl( d, b);

if( last == NULL) // List empty?

first = last = pEl;

else last->next = pEl, last = pEl;

}

// Deletes an element from the beginning of the list void List::popFront()

{ if( first != NULL) // Not empty?

{ ListEl *pEl = first; // Save the first element first = first->next; // Move to the next element delete pEl; // Former first element if( first == NULL) // Empty now?

last = NULL;

} }

// Global functions for output -// Outputs an element:

ostream& operator<<( ostream& os, const ListEl& le) {

os << le.getDate().asString() << " Amount: ";

os << fixed << setprecision(2) << setw(10)

<< le.getAmount();

return os;

}

// Outputs the list:

ostream& operator<<( ostream& os, const List& List) {

ListEl *pEl = List.front();

if( pEl == NULL)

os << "The list is empty!" << endl;

for( ; pEl != NULL; pEl = pEl->getNext() )

os << *pEl << endl;

return os;

}

// Tests the List class.

//

-#include "List.h"

int main()

{

cout << "\n * * * Testing the class list * * *\n"

<< endl;

List aList; // A list

cout << aList << endl; // List is still empty

cout << "\nEnter account changes (Date and Amount)"

"\n(Type invalid input to quit, e.g q):\n";

Date date;

int month, day, year; char c;

double amount;

while( true)

{

cout << "Date format Month-Day-Year : ";

if( !(cin >> month >> c >> day >> c >> year)

|| ! date.setDate( month, day, year) )

break; // Invalid date

cout << "Account change: ";

if( !(cin >> amount) ) break;

aList.pushBack( date, amount);

}

cout << "\nContent of the list:\n";

cout << aList << endl;

cout << "\nRemoving the first element of the list:\n";

ListEl *ptrEl = ptrEl = aList.front();

if( ptrEl != NULL)

{

cout << "Deleting: " << *ptrEl << endl;

aList.popFront();

}

cout << "\nContent of the list:\n";

cout << aList << endl;

return 0;

}

4 7 7

Dynamic Members

This chapter describes how to implement classes containing pointers to dynamically allocated memory.These include

■ your own copy constructor definition and

■ overloading the assignment operator.

A class designed to represent arrays of any given length is used as a sample application.

4.1 6.5 8.2 2.7

Object fArr arrPtr max: 10 cnt: 4

// A class representing dynamic arrays of floats // -class FloatArr

{ private:

float* arrPtr; // Dynamic member int max; // Maximum quantity without

// reallocating new storage int cnt; // Number of present elements public:

// Public methods here };

■ MEMBERS OF VARYING LENGTH

An object of class FloatArrin memory

Data members of class FloatArr