Thread: Upper case output

  1. #1
    Registered User
    Join Date
    Mar 2007

    Upper case output

    Hi I am new to C++ programming and I am in some need of help. I need to write a program that opens a file called "in.dat", reads it character by character and converts all lower case characters to upper case. The program then needs to write this output to a file called "out.dat" and outputs its contents to the screen. This is what I have so far:

    #include <iostream>
    #include <cctype>
    #include <fstream>
       using namespace std;
    int main()
       ifstream inFile("in.dat");
       ofstream outFile("out.dat");
       if (!inFile)
          cout << "Input file not open" << endl;
          return -1;
       if (!outFile)
          cout << "Output file not open" << endl;
          return -1;
       char ch;
       while (ch = inFile.get())
       return 0;
    I already have some text for "in.dat" but this code only loops a character infinitely to the screen. Any help would be appreciated. Thanks.

  2. #2
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    inFile.get() returns an int, not a char. When it attempts to read and finds that the end of file has been reached it returns EOF, which is a negative value. Since it is non-zero, it evaluates to true, hence your loop keeps on going even when the end of file has been reached.

    I suggest using while (inFile.get(ch)) instead.
    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

  3. #3
    Registered User
    Join Date
    Mar 2007
    It's OK people, I've worked it out. Thanks for the help

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