A Complete Guide to Programming in C++ part 43 doc

Exercise 3// ---// Account_rw.cpp // Writes an array with objects of class Account to // a file and feed the array into another array... // Type of a list element:struct Element { string

default: // Invalid call to the program.

cerr << usage << endl;

return 2; // or: exit(2);

}

if( strlen(dest) == 0) // Only source file?

{ // yes ==> output to cout

ifstream infile(source);

if( !infile )

openerror( source);

ok = copy( infile, cout);

// The file is closed by the ifstream destructor

}

else // Copy source to destination { // file in binary mode

ifstream infile( source, ios::in | ios::binary);

if( !infile )

openerror( source);

else

{

ofstream outfile( dest, ios::out | ios::binary);

if( !outfile)

openerror( dest);

ok = copy( infile, outfile);

if( ok)

cerr << "File " << source << " to file "

<< dest <<" copied!"<< endl;

}

}

if(!ok)

{ cerr << "Error while copying!" << endl;

return 3;

}

return 0;

}

bool copy( istream& is, ostream& os) // To copy

{ // is to os

const int BufSize = 1024;

char buf[BufSize];

do

{

is.read( buf, BufSize);

if( is.gcount() > 0)

os.write(buf, is.gcount());

}

while( !is.eof() && !is.fail() && !os.fail() );

if( !is.eof() ) return false;

else return true;

}

Exercise 2

// -// Pizza.h

// Header file for Pizza_W.cpp and Pizza_R.cpp

//

-#include <iostream>

#include <iomanip>

#include <fstream>

using namespace std;

// Structure of a record:

struct Pizza { char name[32]; float price; };

#define MAXCNT 20 // Maximum number of pizzas

#define FILENAME "pizza.fle"

inline void header() {

cout << " * * * P I Z Z A P R O N T O * * *\n\n"

<< endl;

} // -// Pizza_w.cpp

// Demonstrating blockwise writing of records

//

-#include "Pizza.h"

Pizza pizzaMenu[MAXCNT] = {

{ "Pepperoni", 9.90F }, { "White Pizza", 15.90F }, { "Ham Pizza", 12.50F }, { "Calzone", 14.90F } };

int cnt = 4;

char pizzaFile[256] = FILENAME;

int main() // Write records

{ int i;

header();

cout << "\nOur standard offer:\n" << endl;

cout << fixed << setprecision(2);

for( i = 0; i < cnt; ++i) cout << setw(20) << pizzaMenu[i].name

<< setw(10) << pizzaMenu[i].price << endl;

cout << "\n -\n"

<< endl;

// Input more pizzas via keyboard:

while( cnt < MAXCNT)

{

cin.sync(); cin.clear();

cout << "What pizza should be added "

<< "to the menu?\n\n" << "Name: ";

cin.getline( pizzaMenu[cnt].name, 32);

if( pizzaMenu[cnt].name[0] == '\0')

break;

cout << "Price: ";

cin >> pizzaMenu[cnt].price;

if( !cin)

cerr << "Invalid input!" << endl;

else

++cnt;

if( cnt < MAXCNT)

cout << "\n and the next pizza!\n"

<< "Stop with <Return>.\n";

}

// Add data to the file:

int exitCode = 0;

ofstream outFile( pizzaFile, ios::out | ios::binary);

if( !outFile)

{

cerr << "Error opening the file!" << endl;

exitCode = 1;

}

else

{

for( int i = 0; i < cnt; ++i)

if( !outFile.write( (char*)&pizzaMenu[i],

sizeof(Pizza)) ) {

cerr << "Error writing to file!"

<< endl;

exitCode = 2;

}

}

if( exitCode == 0)

cout << "\nData added to file " << pizzaFile

<< ".\n" << endl;

return exitCode;

}

// -// Pizza_r.cpp

// Demonstrating block by block reading of records

//

-#include "Pizza.h"

char pizzaFile[256] = FILENAME;

int main() // Read and display records

{ header();

ifstream inFile( pizzaFile, ios::in | ios::binary); if( !inFile)

{ cerr << "Pizza file does not exist!" << endl;

return 1;

} Pizza onePizza;

int cnt = 0;

cout << "\n -"

<< "\nThe available pizzas:\n" << endl;

cout << fixed << setprecision(2);

while( true) if( !inFile.read( (char*)&onePizza, sizeof(Pizza)) ) break;

else { cout << setw(20) << onePizza.name

<< setw(10) << onePizza.price << endl;

++cnt;

} cout << "\n -\n"

<< endl;

if( !inFile.eof()) {

cerr << "Error reading file!" << endl;

return 2;

} else cerr << "These are " << cnt << " pizzas!\n" << endl; return 0;

}

Exercise 3

// -// Account_rw.cpp

// Writes an array with objects of class Account to

// a file and feed the array into another array

//

-#include "Account.h" // Definition of the class Account

#include <iostream>

#include <fstream>

using namespace std;

Account AccTab1[3] =

{

Account("Lucky, Luke", 707070, -1200.99),

Account("Mickey, Mouse", 123000, 2500.0),

Account("Snoopy, Dog\n" // String can contain more

"Cell #: 01771234567", 543001) // than one line };

Account AccTab2[3]; // Calls to default constructor

int cnt = 3;

char file[] = "account.fle";

int main()

{

int i = 0;

// Write accounts to file

-ofstream outFile( file, ios::out | ios::binary );

if( ! outFile)

{

cerr << "Error opening file " << file

<< endl;

return 1;

}

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

if( !AccTab1[i].write(outFile) )

{

cerr << "Error writing to file " << file

<< endl;

return 2;

}

outFile.close();

// Reads accounts from file -ifstream inFile( file, ios::out | ios::binary );

if( ! inFile) {

cerr << "Error opening file " << file

<< endl;

return 3;

} for( i = 0; i < cnt; ++i) if( !AccTab2[i].read(inFile) ) {

cerr << "Error reading file " << file

<< endl;

return 4;

} inFile.close();

// Displays the accounts read -cout << "The file " << file << " contains the "

<< "following accounts:" << endl;

for( i = 0; i < cnt; ++i) AccTab2[i].display();

cout << endl;

return 0;

}

Exercise 4

// -// telList.h

// A class TelList to represent a list // containing names and telephone numbers

// The methods load(), save(), and saveAs() serve for // loading and saving a telephone list

// -

-#ifndef _TelList_

#define _TelList_

#include <string>

using namespace std;

#define PSEUDO -1 // Pseudo position

#define MAX 100 // Maximum number of elements

// Type of a list element:

struct Element { string name, telNr; };

class TelList

{

private:

Element v[MAX]; // The array and the actual

int count; // number of elements

string filename; // File name

bool dirty; // true if data has been changed

// but not yet saved

public:

TelList() : count(0), filename(""), dirty(false)

{}

int getCount() { return count; }

Element *retrieve( int i )

{

return (i >= 0 && i < count)? &v[i] : NULL;

}

bool append( const Element& el )

{

return append( el.name, el.telNr);

}

bool append( const string& name, const string& telNr); bool erase( const string& name);

int search( const string& name) const;

void print() const;

int print( const string& name) const;

int getNewEntries();

const string& getFilename() const { return filename; } bool setFilename( const string& fn)

{ if( fn.empty()

return false;

else { filename = fn; dirty = true; return true; } }

bool isDirty() const { return dirty; }

bool load();

bool save();

bool saveAs();

};

#endif // _TelList_

// -// TelList.cpp

// Implements the methods of class TelList

//

-#include "telList.h" // Definition of class TelList

#include <iostream>

#include <iomanip>

#include <fstream>

using namespace std;

bool TelList::append( const string& name,

const string& telNr) {

if( count < MAX // Any space

&& name.length() > 1 // minimum 2 characters

&& search(name) == PSEUDO) // does not exist {

v[count].name = name;

v[count].telNr = telNr;

++count;

dirty = true;

return true;

} return false;

} bool TelList::erase( const string& key ) {

int i = search(key);

if( i != PSEUDO ) {

if( i != count-1) // Copy the last element v[i] = v[count-1]; // to position i

count;

dirty = true;

return true;

} return false;

} // -// Methods search(), print(), getNewEntries()

// are unchanged (refer to solutions of chapter 16)

// -// Methods for loading and saving the telephone list

bool TelList::load() {

cout << "\n - Load the telephone list "

<< "from a file -" << "\nFile: ";

string file; // Input file name cin.sync(); cin.clear(); // No previous input getline( cin, file);

if( file.empty()) {

cerr << "No filename declared!" << endl;

return false;

}

// Open the file for reading:

ifstream infile( file.c_str(), ios::in | ios::binary);

if( !infile )

{

cerr << "File " << file

<< " could not be opened!" << endl;

return false;

}

int i = 0;

while( i < MAX)

{

getline( infile, v[i].name, '\0');

getline( infile, v[i].telNr, '\0');

if( !infile)

break;

else

++i;

}

if( i == MAX)

cerr << "Max capacity " << MAX

<< " has been reached!" << endl;

else if( !infile.eof())

{

cerr << "Error reading file " << file << endl;

return false;

}

count = i;

filename = file;

dirty = false;

return true;

}

bool TelList::saveAs()

{

cout << " Save the telephone list in a file "

<< "\nFile: ";

string file; // Input file name

cin.sync(); cin.clear(); // No previous input

getline( cin, file);

if( !setFilename(file))

{

cerr << "No file name declared!" << endl;

return false;

}

else

return save();

}

bool TelList::save() // Save the telephone list.

{ if( filename.empty()) return saveAs();

if( !dirty) return true;

ofstream outfile( filename.c_str(),

ios::out | ios::binary);

if( !outfile ) {

cerr << "File " << filename

<< " could not be opened!" << endl;

return false;

} int i = 0;

while( i < count) {

outfile << v[i].name << '\0';

outfile << v[i].telNr << '\0';

if( !outfile) break;

else ++i;

} if( i < count) {

cerr << "Error writing to file " << filename << endl; return false;

} dirty = false;

return true;

} // -// TelList_.cpp

// Organize a telephone list with class TelList

//

-#include "telList.h" // Definition of class TelList

#include <iostream>

#include <string>

#include <cctype>

using namespace std;

inline void cls() {

cout << "\033[2J\n"; // If ANSI control characters are } // not available, output new-lines