inputing into files

calculus87 · #1 22-Sep-2003, 12:48

Hello,
Here is my question. I have a program where I have 2 functions. The first function (main) gathers two inputs of type string. I also remove the origional file so as to get rid of any left over text.
The other function is able to take one string at a time and place it into a file. Now the problem is when I run the program and I open up the file, only the last string is in the file, and not both.
Here is the code.

CPP / C++ / C Code:

#include <iostream>
#include <stdlib.h>
#include <fstream>
using namespace std;
#include <string>
#include "time.h"
#include <vector>
#include <algorithm>
#include <sstream>

void f1(string text)
{
fstream op;
op.open("output.txt",ios:: out);
op<<text<<endl;
op.close();
}

void main()
{
remove("output.txt");
string a,b;
cout<<"enter string 1"<<endl;
cin>>a;
cout<<"enter string 2"<<endl;
cin>>b;
f1(a);
f1(b);
}

I understand that I could make f1 just take 2 strings but I need to do it this way.
Any ideas?

Thanks,
Ronald

Garth Farley · #2 23-Sep-2003, 03:47

The f1() function is reopening the file each time, but the file pointer is at the beginning of the file by default, so it's overwriting what's there each time you write to it.

You can set it up to append data to the end by adding ios::app to the open() function, like so:

CPP / C++ / C Code:

fstream op;
op.open("output.txt",ios:: out | ios::app);

However you are wasting time reopening a file each time you wish to write to it - unless you're worried about file locking - so I'd suggest you leave it open as long as you need it.

GF

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