C++ increment ID 问题 - JBTALKS.CC

#include <iostream>
#include <fstream>
#include<iomanip>
#include <string>
using namespace std;
//--------------------------------CLASS--------------------------------
class IMDB
{
private:
char mvName[20];
float rating;
int mvID;
public:
void getMV();
void getMVEdit();
void showMV();
void showMVEdit();
int deleteID();
};//end class
//Insert all the movie details
void IMDB::getMV()
{
//read all file to get the ID and the ID is auto increment by 1
IMDB st;
ifstream thisfile;
thisfile.open("Movie Record.dat",ios::binary);
if(!thisfile.eof())
{
mvID = 1;
}
while(thisfile.read(reinterpret_cast<char *> (&st), sizeof(IMDB)))
{
++mvID;
}
thisfile.close();
cout << "Movie ID: " << mvID << endl;
//Enter all the record
cout << "Enter movie name: ";
cin.ignore(1000,'\n');
cin.getline(mvName,20);
cout << "Enter movie rating(0-5): ";
while((!(cin >> rating)) || (rating < 0 || rating > 5))
{
cout << "Enter number between 0-5! Please try again: ";
cin.clear();
cin.ignore (1000,'\n');
}
}
//Display all the movie have been added
void IMDB::showMV()
{
cout << "Movie ID: " << mvID;
cout << "\nMovie Name: " << mvName;
cout << "\nRating: " << fixed << showpoint << setprecision(1) <<rating << endl;
}
//Return the movie ID for the purpose of delete
int IMDB::deleteID()
{
return mvID;
}
//--------------------------------FUNCTION DEFINATION--------------------------------
void displayMenu()
{
cout << "Welcome, What would you like to do?\n"
<< "1 => Add a Movie\n"
<< "2 => View a Movie\n"
<< "3 => Delete a Movie\n"
<< "4 => Quit\n"
<< endl;
cout << "Choice => ";
}
//*****************************FUNCTION WRITE MOVIE*****************************
void writeMV()
{
IMDB st;
ofstream myfile;
//create new file name name Movie Record.dat
myfile.open("Movie Record.dat",ios::binary | ios::app);
st.getMV();//get data from getMV()
myfile.write(reinterpret_cast<char *> (&st), sizeof(IMDB));
myfile.close();
system("PAUSE");
}
//*****************************FUNCTION DISPLAY MOVIE*****************************
void displayMV()
{
IMDB st;
ifstream thisfile;
thisfile.open("Movie Record.dat",ios::binary);
if(!thisfile)
{
cout << "You haven't insert any record yet!\n";
}
//Display all the record
while(thisfile.read(reinterpret_cast<char *> (&st), sizeof(IMDB)))
{
st.showMV();
cout << "\n--------------------------------------\n";
}
thisfile.close();
system("PAUSE");
}
//***************************FUNCTION DELETE MOVIE***************************
void deleteMV(int number)
{
IMDB st;
ifstream thisfile;
thisfile.open("Movie Record.dat", ios::binary);
if(!thisfile)
{
cout<<"You haven't insert any record yet!\n";
}
else
{
cout << "Enter movie ID to delete the record: ";
while(!(cin >> number))
{
cout << "Enter number only! Please try again: ";
cin.clear();
cin.ignore (1000,'\n');
}
}
ofstream myfile;
myfile.open("Temp.dat",ios::out);
thisfile.seekg(0,ios::beg);//read the file from beginning
while(thisfile.read(reinterpret_cast<char *> (&st), sizeof(IMDB)))
{
if(st.deleteID()!= number)
{
myfile.write(reinterpret_cast<char *> (&st), sizeof(IMDB));
}
}
myfile.close();
thisfile.close();
remove("Movie Record.dat");
rename("Temp.dat","Movie Record.dat");
cout << "Movie successful deleted!" << endl;
system("PAUSE");
}
//--------------------------------MAIN FUNCTION--------------------------------
int main()
{
int number;
int selectOpt;
bool done = false;
do
{
displayMenu();
cin >> selectOpt;
switch(selectOpt)
{
case 1 : writeMV();break;
case 2 : displayMV();break;
case 3 : deleteMV(number);break;
case 4 : done = true;
break;
default : cout << "Invalid selection, try again!" << endl;
cin.clear();
cin.ignore (1000, '\n');
system("PAUSE");
}
}while(!done);
system("PAUSE");
return 0;
}

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void deleteMV(int number)

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void deleteMV()

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int number;

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