в 14:21, 25 мая 2010

2010-05-25T14:21:06Z

Admin: 1 версия: Импорт контента...

2010-05-25T10:24:04Z

1 версия: Импорт контента...

Новая страница

==reads the inventory file created by the previous program and displays its contents on the screen:==

<source lang="cpp">
#include <iostream>
#include <fstream>
using namespace std;

int main()
{
ifstream in("INVNTRY"); // input

if(!in) {
cout << "Cannot open INVENTORY file.\n";
return 1;
}

char item[20];
float cost;

in >> item >> cost;
cout << item << " " << cost << "\n";
in >> item >> cost;
cout << item << " " << cost << "\n";
in >> item >> cost;
cout << item << " " << cost << "\n";

in.close();
return 0;
}

</source>

==Save object to file with customized operator==

<source lang="cpp">
#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;

class phonebook {
char name[80];
char areacode[4];
char prefix[4];
char num[5];
public:
phonebook() { };
phonebook(char *n, char *a, char *p, char *nm)
{
strcpy(name, n);
strcpy(areacode, a);
strcpy(prefix, p);
strcpy(num, nm);
}
friend ostream &operator<<(ostream &stream, phonebook o);
friend istream &operator>>(istream &stream, phonebook &o);
};

ostream &operator<<(ostream &stream, phonebook o)
{
stream << o.name << " ";
stream << "(" << o.areacode << ") ";
stream << o.prefix << "-";
stream << o.num << "\n";
return stream; // must return stream
}

istream &operator>>(istream &stream, phonebook &o)
{
cout << "Enter name: ";
stream >> o.name;
cout << "Enter area code: ";
stream >> o.areacode;
cout << "Enter prefix: ";
stream >> o.prefix;
cout << "Enter number: ";
stream >> o.num;
cout << "\n";
return stream;
}

int main()
{
phonebook a;
char c;

fstream pb("phone", ios::in | ios::out | ios::app);

if(!pb) {
cout << "Cannot open phone book file.\n";
return 1;
}

cin >> a;
cout << "Entry is: ";
cout << a; // show on screen
pb << a; // write to disk
char ch;
pb.seekg(0, ios::beg);
while(!pb.eof()) {
pb.get(ch);
if(!pb.eof()) cout << ch;
}
pb.clear(); // reset eof
cout << endl;

pb.close();

}

</source>

==Using Command-Line Arguments to Get a Filename==

<source lang="cpp">
#include <fstream>
#include <iostream>
using namespace std;
class Animal
{
public:
Animal(int weight,long days):itsWeight(weight),DaysAlive(days){}
~Animal(){}
int GetWeight()const { return itsWeight; }
void SetWeight(int weight) { itsWeight = weight; }
long GetDaysAlive()const { return DaysAlive; }
void SetDaysAlive(long days) { DaysAlive = days; }
private:
int itsWeight;
long DaysAlive;
};
int main(int argc, char *argv[])
{
if (argc != 2)
{
cout << "Usage: " << argv[0] << " <filename>" << endl;
return(1);
}
ofstream fout(argv[1],ios::binary);
if (!fout)
{
cout << "Unable to open " << argv[1] << " for writing.\n";
return(1);
}
Animal Bear(50,100);
fout.write((char*) &Bear,sizeof Bear);
fout.close();
ifstream fin(argv[1],ios::binary);
if (!fin)
{
cout << "Unable to open " << argv[1] << " for reading.\n";
return(1);
}
Animal BearTwo(1,1);
cout << "BearTwo weight: " << BearTwo.GetWeight() << endl;
cout << "BearTwo days: " << BearTwo.GetDaysAlive() << endl;
fin.read((char*) &BearTwo, sizeof BearTwo);
cout << "BearTwo weight: " << BearTwo.GetWeight() << endl;
cout << "BearTwo days: " << BearTwo.GetDaysAlive() << endl;
fin.close();
return 0;
}

</source>

← Предыдущая	Версия 14:21, 25 мая 2010
(нет различий)

C++/File/Object Serialization - История изменений

в 14:21, 25 мая 2010

Admin: 1 версия: Импорт контента...