File IO - Tutorial is wrong?

This is a discussion on File IO - Tutorial is wrong? within the C++ Programming forums, part of the General Programming Boards category; I was checking through the tutorials (again), and I got to lesson #10 where it says: Code: #include <fstream.h> #include ...

  1. #1
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    File IO - Tutorial is wrong?

    I was checking through the tutorials (again), and I got to lesson #10 where it says:

    Code:
    #include <fstream.h>
    #include <iostream.h>
    int main()
    {
      char str[10];  
             //Used later
      ofstream a_file("example.txt");
    //Creates an instance of ofstream, and opens example.txt
      a_file<<"This text will now be inside of example.txt"; 
    //Outputs to example.txt through a_file
      a_file.close();                           
    //Closes up the file
       ifstream b_file("example.txt"); 
    //Opens for reading the file
      b_file>>str;    
                 //Reads one string from the file
      cout<<str;   
               //Should output 'this'
      b_file.close();    
               //Do not forget this! 
    }
    The thing is that this doesn't create a file called "example.txt" anywhere...
    Is it just my comp, or what?

  2. #2
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    It worked for me. The file is in the same folder as the
    executable. If you want the file elsewhere put in the full path
    in the code.

  3. #3
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    Aargh! It doesn't seem to work...

    I am using Dev-C++ on a WinXP comp.

    ---------------------------------------------
    Wait, so if I wanted to create a file inside another folder, I use:
    Code:
    ofstream some_file("C:\damn\foo\bar.txt");
    Last edited by NetPsycho; 06-01-2003 at 10:58 AM.

  4. #4
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    I used this code:
    Code:
    #include <fstream.h>
    #include <iostream.h>
    #include <string.h>
    #include <errno.h>
    #include <stdlib.h>
    
    int main()
    {
      char str[10]; 
      //Used later
      ofstream a_file("example.txt");
      if ( !a_file ) {
        cerr << "oops " << strerror(errno) << endl;
        system("pause");
        return 1;
      }
      else
      {
       cout << "Foo" << endl;
       system("pause");
       return 0;
      }
    }
    And it output: Foo

    Ok, I forgot the escapes, but I was not really being very specific.
    Last edited by NetPsycho; 06-01-2003 at 01:01 PM.

  5. #5
    Registered User major_small's Avatar
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    instead of:
    Code:
    ofstream a_file("example.txt");
    try:
    Code:
    ofstream a_file;
    a_file.open("example.txt",ios::trunc);
    ...
    a_file.close();
    it shouldn't make any difference, but maybe your compiler is playing tricks with your head... maybe closing the file will help...
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  6. #6
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    I doubt this is the problem, but with your compiler it might be necessary for you to explicitly enable output to the file by setting the ios::out bit when opening the file. Try this code:

    Code:
    #include <iostream>
    #include <fstream>
    
    using namespace std;
    
    int main(int argc, char** argv) {
    
    	ofstream MyFile;
    
    	//Open file
    	MyFile.open("example.txt", ostream::out);
    
    	if(MyFile.fail()) {
    		cerr <<"Sorry, I can't open that file for output\n";
    		return 0;
    	}
    
    	//Write to file
    	MyFile <<"This should be inside of example.txt" <<endl;
    
    	//Close file
    	MyFile.close();
    }
    That should create the file and write to it. If it doesn't, it should say it couldn't open the file. Hope that helps

  7. #7
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    You will probably find example.txt in your Dev-C++ directory ... i.e. C:\program files\Dev-C++

    To specify a complete path type it this way:

    ofstream a_file("c:/cfiles/scrap/example.txt"); // note - forward slashes

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