即使应该，我的代码也不会覆盖文本文件？

Question

We did a very similar type of code in C++ class but my version isn't working right, even though it is line-by-line (almost) the same.

My code is meant to save a user's Pokemon and they can add and delete as they please. My display function is working but my add and delete function are not. All the files are opening, but it's not overwriting the file like it's supposed to. Really unsure of what to do, I'm very much a beginner and I don't know much.

Here is what I've got so far:

string name[100];
string type[100];
int level[100];
string newPokemon;
string newType;
int newLevel;
ifstream fin;
ofstream fout;
int numberOfPokemon = 0;
//Input Pokemon Info
cout << "Name of Pokemon: ";
getline(cin, newPokemon);
cin.ignore(100, '\n');
cout << "Pokemon type: ";
getline(cin, newType);
cin.ignore(100, '\n');
cout << "Pokemon level: "; //weird gap between "Pokemon type" and "pokemon level". I have to press enter twice from "pokemon type" to get to "pokemon level"
cin >> newLevel;
cin.ignore(5, '\n');
fin.open("pokemon.txt");
//Put file in array
if (fin.is_open())
{
    while (isalnum(fin.peek()) && numberOfPokemon < 100)
    {
        getline(fin, name[numberOfPokemon]);
        getline(fin, type[numberOfPokemon]);
        fin >> level[numberOfPokemon];
        fin.ignore(100, '\n');
        if (name[numberOfPokemon] != newPokemon)
            numberOfPokemon++;
    }
    fin.close();
}
//Output file
fout.open("pokemon.txt");
if (fout.is_open())
{
    for (int i = 0; i < numberOfPokemon; i++)
    {
        fout << name[i] << "\n";
        fout << type[i] << "\n";
        fout << level[i] << "\n";

    }
    //Tack on new piece
    fout << newPokemon << "\n";
    fout << newType << "\n";
    fout << newLevel << "\n";
    fout.close();
    cout << "Add Successful\n";
}
else
{
    cout << "Add Failure\n";
}

and now my delete function:

string name[100];
string type[100];
int level[100];
int pokemonCount = 0;
string deletedPokemon = "";
bool found = false;

ifstream fin;

cout << "Which Pokemon would you like to delete?" << endl;
getline(cin, deletedPokemon);
cin.ignore(5, '\n');

fin.open("pokemon.txt");
if (fin.is_open())
{
    while (isalnum(fin.peek()))
    {
        getline(fin, name[pokemonCount]);
        getline(fin, type[pokemonCount]);
        fin >> level[pokemonCount];
        fin.clear();
        fin.ignore(100, '\n');
        if (deletedPokemon == name[pokemonCount])
        {
            pokemonCount--;
            found = true;
        }
        pokemonCount++;
    }
    fin.close();
    cout << "ya the file opened" << endl; //always appears
}

ofstream fout;
fout.open("pokemon.txt");
if (fout.is_open())
{
    for (int i = 0; i < pokemonCount; i++)
    {
        fout << name[i] << "\n";
        fout << type[i] << "\n";
        fout << level[i] << endl;
    }
    fout.close();
    cout << "pokemon removed\n";
    cout << "the file opened."; //it is returning that the file opened in both occasions in this function but nothing is happening!
}
else
{
   cout << "removal failure";
   cout << "The file didn't open";
}
return found;

at the end of this function (if I chose to delete one), it will offer the "Would you like to add a Pokemon?" but it wont let me input an answer and it will just end the program.

Answer 1

The default behaviour of ofstream::open is to simply open the file for reading and writing. If you want to overwrite the file, you need to specify it in your call to open .

fout.open("pokemon.txt", ios_base::in|ios_base::out|ios_base::trunc);

Answer 2

Make sure your file is not marked as read-only under properties.

Also, there is a bug in your delete function:

The bfound should be replace with nDelete pokemon and when you write out the file:

    if (deletedPokemon == name[pokemonCount])
    {
        pokemonCount--;
        found = true;
        nDeleteIndex = i;
    }
....
    for (int i = 0; i < pokemonCount; i++)
    {

    if(i == nDeleteIndex)
        continue;
    fout << name[i] << "\n";
    fout << type[i] << "\n";
    fout << level[i] << endl;
    }

Right now it will re-write all your pokemons without skipping the one you want to delete!

Also, what happens if the user has 155 pokemons for a full index. You want to use:

 std::vector<string> names;
 ....
 string szPokemon;
 getline(fin, name[numberOfPokemon]);
 names.push_back(szPokemon);

Thus you no longer have a limit !

Answer 3

Here is much cleaner code, its much more maintainable and whenever you add/remove a field from the pokemon (Shiny? Male/Female ? Unique ?) you will be able to easily do it inside the CPokemonObject instead of having to copy paste the code 100 times.

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <vector>

using namespace std;
#define POKEMON_FILE "Pokemon.txt"

class CPokemon
{
public:
    string szName;
    string szType;
    int nLevel;
    CPokemon() : szName("Pika"), nLevel(10), szType("Lightning")
    {};

    void Read(ifstream &file)
    {
        file >> szName;
        file >> szType;
        file >> nLevel;
    };

    void Write(ofstream &file)
    {
        file << szName << endl;
        file << szType << endl;
        file << nLevel << endl;
    };

    void CreatePokemon()
    {
        //Input Pokemon Info
        cout << "Name of Pokemon: ";
        getline(cin, szName);
        cout << "Pokemon type: ";
        getline(cin, szType);
        cout << "Pokemon level: "; //weird gap between "Pokemon type" and "pokemon level". I have to press enter twice from "pokemon type" to get to "pokemon level"
        cin >> nLevel;
    }
};

void WritePokemons(vector<CPokemon>& Pokemons)
{
    ofstream fout;
    fout.open(POKEMON_FILE);

    //check the file open
    if (!fout.is_open())
    {
        cout << "removal failure";
        cout << "The file didn't open";
        return;
    }

    //Write out all the pokemons
    for (unsigned int i = 0; i < Pokemons.size(); i++)  
        Pokemons[i].Write(fout);

    fout.close();
}

void ReadPokemons(vector<CPokemon>& Pokemons)
{
    ifstream fin;
    fin.open(POKEMON_FILE);
    if (fin.is_open())
    {
        while (isalnum(fin.peek()))
        {
            CPokemon Pokemon;
            Pokemon.Read(fin);
            Pokemons.push_back(Pokemon);
        }
        fin.close();
        cout << "ya the file opened" << endl; //always appears
    }
}

bool DeletePokemon()
{
    vector<CPokemon> Pokemons;

    string szPokemonToDelete = "";
    cout << "Which Pokemon would you like to delete?" << endl;
    cin >> szPokemonToDelete;

    //Read all pokemons
    ReadPokemons(Pokemons);

    ofstream fout;
    fout.open("pokemon.txt");

    //check the file open
    if (!fout.is_open())
    {
        cout << "removal failure";
        cout << "The file didn't open";
        return false;
    }

    bool bFound = false;
    for (unsigned int i = 0; i < Pokemons.size(); i++)      
    {
        //Skip the pokemon to delete
        if(Pokemons[i].szName == szPokemonToDelete)
        {
            bFound = true; //we found the pokemon to delete
            continue;
        }

        Pokemons[i].Write(fout);
    }

    fout.close();

    return bFound;
}

void AddPokemon()
{
    vector<CPokemon> Pokemons;

    //Read all pokemons from the file
    ReadPokemons(Pokemons);

    //Create the new porkemon
    CPokemon Pokemon;
    Pokemon.CreatePokemon();

    //Add the pokemon to the list
    Pokemons.push_back(Pokemon);

    //Output file
    WritePokemons(Pokemons);
}