Thread: passing an ofstream by reference

  1. #1
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    passing an ofstream by reference

    This may be a silly question, but here goes. Is there any way I can pass cout as a parameter(by reference of course) into a function that takes an ofstream& as opposed to an ostream&? Basically I have a function that gets an ofstream& as a parameter so that it can continue writing to a pre-defined and pre-opened file. However, I just found the need to also have that function print to the screen. I could make a new function, but it is a fair amount of code and it would be identical. Any ideas?

    Would it be a problem to always pass both?

    Code:
    void function(ostream &sout, ofstream &fout);
    Another question is what is the point of having cin.ignore() after each cin statement. I saw that somewhere and thought I should know.

    One more about classes. Is it necessary to always have a destructor, or do the objects get destroyed anyway after going out of scope?

    Thanks for the help

  2. #2
    C++ Witch laserlight's Avatar
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    Basically I have a function that gets an ofstream& as a parameter so that it can continue writing to a pre-defined and pre-opened file. However, I just found the need to also have that function print to the screen.
    Chances are you can just write for ostream, and then pass the ofstream object.
    e.g.
    Code:
    std::ostream& writeMe(std::ostream& os, int me) {
    	return os << me;
    }
    int main() {
    	//...
    	int num = 1;
    	std::ofstream out(filename);
    	writeMe(out, num);
    	writeMe(std::cout, num);
    	//...
    }
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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