i want to create a warehouse program for school using the random access file management.
i built a class called product(prodotto) with many private var and i must create a new record.
The function checks if the product already exists with the seekg pointer and reading the file. After u can write the file in that space if there is not. the key is the product code (codice).
The issue is that every time i run the function the former record is erased.
before this version i used a general fstream to do the work but it was worse. the file.dat was always empty.
i checked the pointers with tellg and tellp and they are ok. also the reading part seems ok. I think the problem is the writing statement.
this is the function:
void aggiungiProd()
{
int code;
string name,section, description;
int quantity;
double price;
cout<<"\n(insert 0 to come back)"<<endl;
//exit condiction
cout<<"Insert product code:";
cin>>code;
if( cin.good()==0)
{ code=0;
cout<<"invalid code. Please reinsert:"<<endl;
cin>>code;
} //also this part is not working but is less important
if(codice==0) return;//exit condition
ifstream readFile("prod.dat",ios::in);
if(!readFile){
cerr<<"Error during the reading";
exit(1);
}
int var;
var=code-1;
//use a pointer to indicate the location to read
readFile.seekg(var * (sizeof(Prodotto)),ios::beg );
//reading the product record
Prodotto prodotto;
readFile.read(reinterpret_cast< char*> (&prodotto),sizeof(Prodotto));
readFile.close();
if(prodotto.getCod()==0)
{
//THIS PART IS ONLY ABOUT VARIABLES TO SET--> SKIP
cout<<"Inserisci il nome del prodotto (max 30 caratteri): ";
cin.ignore();
getline(cin,name);
if(name=="0") return;//condizione uscita
cout<<"Inserisci quantità da aggiungere: ";
cin>>quantita;
if(quantita==0) return;
cout<<"Inserisci il prezzo del prodotto: " ;
cin>>prezzo;
if(prezzo==0) return;
cout<<"Inserisci sezione di appartenenza del prodotto(max 15 caratteri): " ;
cin.ignore();
getline(cin,sezione);
if(sezione=="0") return;
cout<<"Aggiungi una descrizione del prodotto (max 500 caratteri):";
cin.ignore();
getline(cin,descrizione);
if(descrizione=="0") return;
//END OF THE VARIABLES INSERTION
//NOW PUT THE VARIABLES IN THE PRODUCT prodotto
prodotto.setCod(codice);
prodotto.setNome(nome);
prodotto.setQta(quantita);
prodotto.setPrz(prezzo);
prodotto.setSez(sezione);
prodotto.setDes(descrizione);
//open the file as output
ofstream inOutProd("prod.dat", ios::out );
if(!inOutProd){
cerr<<"Error in the file creation";
exit(1);
}
//pointer for the location of the new record
inOutProd.seekp(var * (sizeof(Prodotto)));
//write the record prodotto
inOutProd.write(reinterpret_cast<const char*>(&prodotto),sizeof(Prodotto));
//i believe the problem is in the statement over this line. I tried also to add ios::app
// in the ofstream line but it only append the new record at the end of file.
cout<<"the following product has been saved successfully\n"<<endl;
outputLine(cout,prodotto);
inOutProd.close();
}
else
{
cerr<<"The product"<<codice<<"is already in our database"<<endl;
}
}
if u can help me i will hug u untill the next Christmas
