How to get input from multiple files?

This is a discussion on How to get input from multiple files? within the C++ Programming forums, part of the General Programming Boards category; Hi, I'm creating a program that needs to read in a filename from stdin, open it, and do some processing, ...

  1. #1
    Registered User
    Join Date
    Oct 2003
    Posts
    9

    How to get input from multiple files?

    Hi,

    I'm creating a program that needs to read in a filename from stdin, open it, and do some processing, then repeat the process until the user enters "quit." I get the first file processed fine, but it crashes when I try to open the second file. Actually, the program enter the if (! inFile) section of code even if the second filename is correct and the file exists. I think it's because the filestream is bad at the end of the first file. There must be some way to reuse the same file handle. Here is what I've got:
    Code:
    int main()
    {
    	ifstream inFile;
    	string inFilename;
    	Maze m1;
    
    	cout << "Enter filename with stored maze or \"quit\" to end: ";
    
    	cin >> inFilename;
    	inFile.open(inFilename.c_str());
    
    	while(inFilename != "quit")
    	{
    		// make sure input file was opened properly
    		if (! inFile)
    		{
    			cout << "Error opening file \"" << inFilename.c_str() << "\"\nProgram will now exit.\n";
    			return 1;
    		}
    
    		m1.readMaze(inFile);
    		m1.printMaze();
    		inFile.close();
    
    		cout << "Enter filename with stored maze or \"quit\" to end: ";
    		cin >> inFilename;
    		inFile.open(inFilename.c_str());
    	}
    
    	return 0;
    }
    Any idea what I've got wrong? Thanks!

  2. #2
    C++ Developer XSquared's Avatar
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    Check out this older thread on pretty well the exact same topic.
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

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  3. #3
    Registered User
    Join Date
    Oct 2003
    Posts
    9
    Thanks, but I just realized I was passing the ifstream object to my function by value instead of by reference! All fixed now.

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