Thread: Writing to a file

Hey guys. I have a problem with writing to a file.

I will try and simplify the problem so it might sound strange.

Lets say I have a function which works out a series of numbers, once each number is found I call another function (say, printnumber). This function writes the number to the output file.

My problem is, the output file seems to only display the last number. I think this is because in the print function i have a piece of code like this

Code:

ofstream output;
output.open (argv);
.....
.....
output.close();

This would sort of over-write the file would it not.

My question is, is there any simple way around this? I have thought about perhaps opening the file only once - outside the first function, but I am unsure how I would send the output file as a function parameter.

Also, another quick question if I may. Say I have two command line parameters (file names). In main, how would I go about doing this :

Code:

ofstream output;
output.open (??argv??);

You can pass an ofstream via a const reference (that is,

Code:

void printnumber(int number, const ofstream& output)

And I think your command-line arguments are going to be in argv[1] and argv[2].

It doesn't make sense to make the ofstream a reference to const, since you write to an ofstream and you can't do that if it is const. A plain reference is more appropriate.