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c++visual-studio-2012creationofstream

Ofstream not creating a new file correctly


I've tried to write a simple database program. The problem is that ofstream does NOT want to make a new file.

Here's an extract from the offending code.

void newd()
{
string name, extension, location, fname;
cout << "Input the filename for the new database (no extension, and no backslashes)." << endl << "> ";
getline(cin, name);
cout << endl << "The extension (no dot). If no extension is added, the default is .cla ." << endl << "> ";
getline(cin, extension);
cout << endl << "The full directory (double backslashes). Enter q to quit." << endl << "Also, just fyi, this will overwrite any files that are already there." << endl << "> ";
getline(cin, location);
cout << endl;
if (extension == "")
{
    extension = "cla";
}
if (location == "q")
{
}
else
{
    fname = location + name + "." + extension;
    cout << fname << endl;
    ofstream writeDB(fname);
    int n = 1; //setting a throwaway inteher
    string tmpField, tmpEntry; //temp variable for newest field, entry
    for(;;)
    {
        cout << "Input the name of the " << n << "th field. If you don't want any more, press enter." << endl;
        getline(cin, tmpField);
        if (tmpField == "")
        {
            break; 
        }
        n++;
        writeDB << tmpField << ": |";
        int j = 1; //another one
        for (;;)
        {
            cout << "Enter the name of the " << j++ << "th entry for " << tmpField << "." << endl << "If you don't want any more, press enter." << endl;
            getline(cin, tmpEntry);
            if (tmpEntry == "")
            {
                break;
            }
            writeDB << " " << tmpEntry << " |";
        }
        writeDB << "¬";
    }
    cout << "Finished writing database. If you want to edit it, open it." << endl;
}
}

EDIT: OK, just tried

#include <fstream>
using namespace std;
int main()
{
ofstream writeDB ("C:\\test.cla");
writeDB << "test";
writeDB.close();
return 0;
}

and that didn't work, so it is access permission problems.


Solution

  • ofstream writeDB(fname); //-> replace fname with fname.c_str()
    

    If you lookup the documentation of the ofstream constructor, you will see something like: explicit ofstream ( const char * filename, ios_base::openmode mode = ios_base::out );

    The second argument is optional, but the first one is a const char*, and not a string. To solve this problem the most simple way is to convert your string to something called a C-string (char*, which is basically an array of chars); to do that just use c_str() (it«s part of the library).

    Other than that, you could just place the information directly on a C-str, and then pass it normally to the ofstream constructor.