file creation

[seshreddy]

Hi

in my application i want to read data from file and incase file doesnot exist then new file has to be created and some default values r written to file.


my doubt is when i use

#include<iostream.h>
#include<fstream.h>

it is working properly.


but now i changed to

#include<iostream>
#include<fstream>
using namespace std;

and it is not creating file when doesnot exist.


the file modes that i have taken are
fstream file;
file.open("cache.txt",ios::in | ios::ate | ios::out);

can any one try this out..

bye
seshu

[Philip Nicoletti]

I seem to remember that the open modes act differently,
but I don't have any documentation in front of me (or
even remember where I saw it ... maybe it was in
a some other codeguru thread).

I think that this work-around does what you want ...


#include <fstream>
#include <iostream>

using namespace std;

void MyOpenFile(std::fstream& file, const char* fname)
{
file.open(fname,std::ios::in);

if (!file.is_open())
{
// file does not exist, create it;
file.close();
file.open(fname,ios::out);
}

// close file and open the way we really want ...
file.close();
file.clear();
file.open(fname,ios::in | ios::ate | ios::out);
}


int main()
{
fstream file;
MyOpenFile(file,"cache.txt");

file << "hello" << endl;


return 0;
}

[seshreddy]

Hi Philip Nicoletti

as u told is work-around only. but we could not find the actual reason.

thank u.

at least u have given me one solution.

when see ur idea though i know that "in"mode is working properly why i did not think like u.


okey bye

seshu