writing to a file when your program has "void"

[Zachary]

Sorry for that horrible title line.

Here's my problem. I've written a program to do some permutation stuff...though the process isn't really relevant. As I worked on it, I always had it "cout" the data to the screen, although eventually I need it to write this info to a text file.

I've done this before, and it's worked fine. I #include <fstream> and then give a command in the main function to ofstream myfile; and myfile.open("filename.txt"); Then change my "cout"s to "myfile"s, and bingo. Works like a charm!

Problem is, I'm trying a modular approach to programming (I think that's the right word), where I have a "static void" function that does the work for me. I haven't had any luck getting it to write to the file.

Here's my code:
[code=c++]
#include <iostream>
#include <fstream>

using namespace std ;

static void show_perm ( int *positions , int position_count )
{
int check1 = 0;
int check2 = 0;
int check3 = 0;
ofstream myfile;
myfile.open ("PermsWithRepeats.txt");

for ( int j = 0 ; j < position_count ; j++ )
{
if (positions[j] == 1)
{
check1 = 1;
}
if (positions[j] == 2)
{
check2 = 1;
}
if (positions[j] == 3)
{
check3 = 1;
}
}
if (check1 == 1 && check2 == 1 && check3 == 1)
{
for (int i = 0; i < position_count; i++)
myfile << positions[i] ; // if these two lines say "cout" instead of "myfile," the info comes up on the display just fine.
myfile << endl ;
}
}

static void show_perms (int *values, int value_count, int *positions, int position_count, int filled_positions)
{
if ( filled_positions == position_count )
{
show_perm ( positions , position_count ) ;
return ;
}
filled_positions ;
for ( int i = 0 ; i < value_count ; i++ )
{
positions [ filled_positions ] = values [ i ] ;
show_perms ( values, value_count, positions, position_count, filled_positions + 1 ) ;
}
}

int main ( )
{
int values[] = {1,2,3};
int positions[4];
show_perms ( values , 3 , positions , 4 , 0 ) ;
return 0 ;
}
[/code]

The program runs, and it even creates the file "PermsWithRepeats.txt," but the file is empty -- nothing gets written to it. I'm sure it's something obvious that I'm missing. Can anyone help?

Thanks!

[Zachary]

I'm guessing that it opens the file each time it goes through static void show_perm and writes over what was in there already. On the last time through the show_perm function, it returns a value that is not supposed to be displayed, because of the if statement in line 29. So that's why the file is empty. (I think)

How can I get it to open the file once, and then add to it each time through the show_perm function? (if that is indeed what's happening)

Thanks!!

[Zachary]

(line 12)
myfile.open ("PermsWithRepeats.txt", fstream::app);

That seems to do it!