Ich habe in meinem C++-Code bemerkt, dass jedes Mal, wenn ich eine std::ofstream Objekt kann ich die Datei nicht wieder öffnen, die ich mit std::ifstream . std::ifstream 's open Funktion wird immer fehlschlagen.
Gibt es etwas "extra" kann ich tun, um sicherzustellen, dass mein std::ofstream-Objekt ordnungsgemäß geschlossen wird?
Wahrscheinlich wird jemand nach meinem speziellen Code fragen, also habe ich ihn hier eingefügt, um diesen Beitrag klein zu halten aquí . In meinem Code werden nach dem Durchlaufen der Fälle a oder d alle std::ifstream offene Anrufe scheitern. (Bevor ich diese Frage gestellt habe, haben mehrere Personen mit meinem Code gespielt, die nichts anderes feststellen konnten, als dass std::ofstream Schließen aus unbekannten Gründen fehlgeschlagen)
Vielen Dank im Voraus für alle Antworten, die Sie erhalten.
Code ist
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
typedef struct Entry
{
string Name;
string Address;
string Phone;
};
int main()
{
bool exit = false, found = false;
char input, ch;
string stringinput, stringoutput;
ifstream fin, ibuffer;
ofstream fout, obuffer;
Entry buffer;
while(!exit)
{
cout << "Welcome to the Address Book Application!" << endl << endl;
cout << "\tSelect an option:" << endl << endl;
cout << "\tA -- Add New Entry" << endl;
cout << "\tD -- Delete an Entry" << endl;
cout << "\tS -- Search for an Existing Entry" << endl;
cout << "\tE -- Exit" << endl << endl;
cin >> input;
switch(input)
{
case 'a':
case 'A':
cin.ignore(255,'\n');//Apparently necessary because an extra new line carrys over in the cin stream
system("cls");
//Get Information from User
cout << "Enter Phone Number: ";
getline(cin, buffer.Phone);
cout << endl << "Enter Name: ";
getline(cin, buffer.Name);
cout << endl << "Enter Address: ";
getline(cin, buffer.Address);
/*Copy existing database into a buffer. In other words, back it up*/
fin.open("address.txt");
if(!fin)
{
fin.close();
fout.open("address.txt");
fout << buffer.Phone << endl << buffer.Name << endl << buffer.Address << endl;
}
if(fin)
{
obuffer.open("buffer.txt");
while(fin && fin.get(ch))
obuffer.put(ch);
fin.close();
obuffer.close();
/*Copy buffer to new database file*/
ibuffer.open("buffer.txt");
fout.open("address.txt");//This removes all of the previously existing info from database.txt
while(ibuffer && ibuffer.get(ch))
fout.put(ch);
ibuffer.close();
remove("buffer.txt");//Delete the buffer
fout << endl << buffer.Phone << endl << buffer.Name << endl << buffer.Address << endl;
}
buffer.Phone.erase();
buffer.Name.erase();
buffer.Address.erase();
fout.close();
break;
case 'd':
case 'D':
cin.ignore(255,'\n');//Apparently necessary because an extra new line carrys over in the cin stream
system("cls");
cout << "Enter the phone number of the entry to delete: ";
cin >> stringinput;
fin.open("address.txt");
if(!fin)
{
cout << endl << "No entries exist!";
fin.close();
break;
}
obuffer.open("buffer.txt");
/* Copy everything over into the buffer besides the account we wish to delete */
while(!fin.eof())
{
fin.read(&ch, sizeof(char));
if(ch != '\n' && ch != '\0')
stringoutput += ch;
if(ch == '\n' || ch == '\0')
{
if(stringinput.compare(stringoutput))
{
stringoutput += ch;
obuffer << stringoutput;
stringoutput.erase();
}
if(!stringinput.compare(stringoutput))
{
stringoutput += ch;
getline(fin, stringoutput);
getline(fin, stringoutput);
fin.read(&ch, sizeof(char));//Get rid of the extra '\n'
stringoutput.erase();
}
}
}
//Hack: Copy the last line over since the loop for some reason doesn't
obuffer << stringoutput;
stringoutput.erase();
fin.close();
obuffer.close();
fout.open("address.txt");
ibuffer.open("buffer.txt");
while(ibuffer && ibuffer.get(ch))
fout.put(ch);
ibuffer.close();
fout.close();
remove("buffer.txt");
cout << endl << "Entry " << stringinput << " deleted successfully!" << endl;
stringinput.erase();
stringoutput.erase();
break;
case 's':
case 'S':
cin.ignore(255,'\n');//Apparently necessary because an extra new line carrys over in the cin stream
system("cls");
found = false;
fin.open("address.txt");
if(!fin)
{
cout << "No entries currently exist!" << endl << endl;
fin.close();
break;
}
cout << "Enter the phone number to search for: ";
cin >> stringinput;
while(!fin.eof())
{
fin.read(&ch, sizeof(char));
if(ch != '\n' && ch != '\0')
stringoutput += ch;
if(ch == '\n' || ch == '\0')
{
if(!stringinput.compare(stringoutput))
{
found = true;
break;
}
stringoutput.erase();
}
}
if(found)
{
cout << "Phone Number: " << stringinput << endl;
getline(fin, stringoutput);
cout << "Name: " << stringoutput << endl;
getline(fin, stringoutput);
cout << "Address: " << stringoutput << endl << endl;
}
if(!found)
{
stringoutput.erase();
cout << endl << stringinput << " is not in the address book!" << endl << endl;
}
stringinput.erase();
stringoutput.erase();
fin.close();
break;
case 'e':
case 'E':
exit = true;
break;
default:
system("cls");
cout << input << " is not a valid option." << endl << endl;
break;
}
}
return 0;
}
