Thread: Selecting any option other than exit results in "This file does not exist"

Hi,

Selecting any option (1-3) results in 'This file does not exist'. I've fiddled around, to no avail. I'm guessing it's something to do with the folder structure the files are actually in, but obviously, I'm not too sure.

The files themselves are in the Visual Studio project folder.

Can anyone help?

Cheers.

Code:

#include <iostream>
#include <fstream>


using namespace std;

int main()


{
    cout << "Willkommen zu meinem Programm!\n\n";
    char choice;
    do {
        //User Prompt
        cout << "Please Choose a Selection from the Menu.\n\n";
        //Display Menu
        cout << "1) Program Languages and their uses\n2) Different Programming Paradigms\n3) Different C++ Features and their uses \n4) Exit\n\n";
        cin >> choice;
        cout << endl;
        if (choice == '1')
        {
            //Read the file
            ifstream infile;
            ofstream outfile;
            //Open the File
            infile.open("ProgrammingLanguages.txt", ios::in);
            //Ensure File exists
            if (!infile)
            {
                cout << "File does not exist!\n\n";
            }
            //Close the file
            infile.close();
        }
        if (choice == '2')
        {
            //Read the file
            ifstream infile;
            ofstream outfile;
            //Open the File
            infile.open("ProgrammingParadigms.txt", ios::in);
            //Ensure File exists
            if (!infile)
            {
                cout << "File does not exist!\n\n";
            }
            //Close the file
            infile.close();
        }
        if (choice == '3')
        {
            //Read the file
            ifstream infile;
            ofstream outfile;
            //Open the File
            infile.open("C++Features.txt", ios::in);
            //Ensure File exists
            if (!infile)
            {
                cout << "File does not exist!\n\n";
            }
            //Close the file
            infile.close();
        }
        else if (choice == '4')
        {
            //Tell user to have nice day
            cout << "A thousand blessings upon you and your family.\n";
            cin.get();
            cin.ignore();
    }


    } while (choice != '4');


    return 0;


}

Hi,

Obviously, the files you wanted to read are no in the same path with your current C++ program. You might have to check that.
There are some improvement you can also make on your code.

Instead of using repeated ifs like you are doing, why not use if/else if? Then why repeat the ifstream and ofstream in every time?
You can place so that all if statement have have access to just one.

Lastly, you are not reading any of the file, so anything is display even if your code works.

Also posted here.

Look closer at the code, the file names are different in every if statement. So keeping the streams local to the block is a good choice.

I get the angle you are pointing at, but even with a different file names, keeping the streams at the top of the if/else if, works good. it using a single
file handler to open different files, as long as the handler is closed lexically; like so:

Code:

        ....
        if (...) {...}
         else if (choice == '3')  {

            //Open the File
            infile.open("myFile.txt", ios::in);

            //Ensure File exists
            if (!infile)
            {
                cout << "File does not exist!\n\n";
            }
             while(getline(infile, line))
            cout << line << endl;

            //Close the file
            infile.close();  // note
        }
       ...

But why worry about having to close the stream? If you keep the stream local the destructor automatically closes the stream when the instance goes out of scope. It is usually better to try to practice the RAII technique whenever possible.

And don't forget that just closing a file and reopening the file doesn't always reset the error flags for the stream.

Jim

Originally Posted by jimblumberg

But why worry about having to close the stream? If you keep the stream local the destructor automatically closes the stream when the instance goes out of scope. It is usually better to try to practice the RAII technique whenever possible.

And don't forget that just closing a file and reopening the file doesn't always reset the error flags for the stream.

Jim

You have a point there.

Maybe the OP could then use a function to do that, instead of repetitions.