ifstream ofstream help

[mastern200]

I need to make a program where it can read from a file and write to it. But the problem is, all i can do is read from it and not write to it. This is the code i have so far:

# include <iostream>
# include <fstream>
# include <cstdlib>
# include <iomanip>
# include <string>
# include <vector>
 
using namespace std;
 
int main()
{
    string filePath = "C:\\documents\\test\\";
    string fileName = "";
    string name = "";
    char character=' ';
 
    ofstream myfile("C:\\documents\\test\\");
    ifstream inputFile;
 
    vector<string>names(4," ");
 
    cout << "Please enter the name of the input file: ";
    getline(cin, fileName);
    fileName = filePath + fileName;
 
    inputFile.open(fileName.c_str());
 
    while(inputFile.get(character)) 
    {
        cout << character;
    }
 
    cin.get();
    cin.get();
    return 0;
}
 

[sicarie]

That's because you just declare it as an ifstream (input file stream), and you want it to be an fstream to both read and write to it.

I personally like cplusplus.com's tutorials, I think they're easy to read and have good examples, but let me know if that doesn't help.

[mastern200]

OK i get it, thanks. But here is the real problem: The program should ask the user where is a text file. The file should open and it will be a list of names. The names should be stored in a vector after being read by the program.The program then will call a function named print that prints to the monitor the list of names, numbered starting with 1. It will ask the user if they want to delete a name, insert a name, or write the names to a file and end the program. The problem here is, i can get the file to open up and display the names, but i can't get it to prompt the user what to do next. It basically just displays the file, but doesnt allow for any editing.

# include <iostream>
# include <fstream>
# include <cstdlib>
# include <iomanip>
# include <string>
# include <vector>
 
using namespace std;
 
int choice=0;
 
int main()
{
    string filePath = "C:\\17\\test\\";
    string fileName = "";
    string name = "";
    char character=' ';
 
    ofstream myfile("C:\\17\\test\\");
    ifstream inputFile;
 
    vector<string>names(4," ");
 
    cout << "Please enter the name of the input file: ";
    getline(cin, fileName);
    fileName = filePath + fileName;
 
    inputFile.open(fileName.c_str());
 
    while(inputFile.get(character)) 
    {
        cout << character;
        cout<<endl;
    }
 
    cout<<"Do you want to:";
    cout<<endl;
    cout<<"1. Delete a name";
    cout<<endl;
    cout<<"2. Insert a name";
    cout<<endl;
    cout<<"3. Write the names to a file and end the program";
    cout<<endl;
    cin>>choice;
 
 
    cin.get();
    cin.get();
    return 0;
}
 

Yes, i am a beginner at C++

[sicarie]

 
    cout<<"Do you want to:";
    cout<<endl;
    cout<<"1. Delete a name";
    cout<<endl;
    cout<<"2. Insert a name";
    cout<<endl;
    cout<<"3. Write the names to a file and end the program";
    cout<<endl;
    cin>>choice;
 
 
    cin.get();
    cin.get();
    return 0;
}
 

You have no control structure for keeping in the program, you just get two inputs and exit. I would recommend using a while loop around the code above, and then you could call whatever functions you wanted to edit or save the vector.

[mastern200]

I know that, thanks, but the problem is how to store the names in the vector after the file is opened.

[sicarie]

I know that, thanks, but the problem is how to store the names in the vector after the file is opened.

    while(inputFile.get(character)) 
    {
        cout << character;
        cout<<endl;
    }
 

You do it there, add each filename to the vector, while you're reading it in, that way you can close your ifstream when you're done with it. I would recommend using getline again, and then if there are multiple elements on one line, strtok() to parse those elements apart.