random access

This is a discussion on random access within the C++ Programming forums, part of the General Programming Boards category; Hi there. I want to read from a text file witch contains five names. The program must display the context ...

  1. #1
    Registered User
    Join Date
    May 2002
    Posts
    23

    random access

    Hi there. I want to read from a text file witch contains five names.
    The program must display the context of the file in reverse order. Now, everything works fine as long as the names are all on the same line, e.g. Tom Boby Sarah Elena George
    but if the names are in separate lines like one name per line then it only desplayes the last name(txt file attached). How do i fix this?

    Thanks for your help




    Code:
    ifstream fp;
    
    int main()
    {
        char in_char;
    
        fp.open("names.txt", ios::in);
    
        if(!fp)
        {
        cout<<"**Error opening file**\n";
        exit(0);
        }
    
        fp.seekg(-1l,ios::end);
    
       while(fp.get(in_char))
        {
         fp.seekg(-2l,ios::cur);
         cout<<in_char;
        }
        fp.close();
        getch();
        return 0;
    }
    Attached Files Attached Files

  2. #2
    Registered User
    Join Date
    May 2002
    Posts
    317
    My guess is that you are reaching the eof, and thus thyat flaqg is set. Therefore in your while(fp.get(in_char)) is returning false and therefore terminating after the first read. Do this:

    [code]

    while(fp.get(in_char))
    {
    fp.clear(); //reset the flag
    fp.seekg(-2l,ios::cur);
    cout<<in_char;

    }

  3. #3
    Registered User
    Join Date
    May 2002
    Posts
    23
    That doesn't seem to work. Also i think that the while loop doesnt return false after the first read because it desplays the last name.

    i put a delay in the loop so i can see what it does and it shows one character at a time -haras (sarah(the last name in the txt file) in reverse) and then it goes to a new line, prints nothing and again the same thing a few more times.

    Code:
     
     while(fp.get(in_char))
        {
        fp.clear();
        fp.seekg(-2l,ios::cur);
        cout<<in_char;
        delay(500);
        }

  4. #4
    Registered User
    Join Date
    May 2002
    Posts
    317
    Sorry about that, here I ran this one myself. It works:

    Code:
        fstream fp;
        char in_char;
    
        fp.open("names.txt", ios::in|ios::binary);
    
        if(!fp)
        {
        cout<<"**Error opening file**\n";
        cin.get();
    	exit(0);
        }
    
        fp.seekg(-1l,ios::end);
    
       while(fp.get(in_char))
        {
           fp.seekg(-2l,ios::cur);
           cout<<in_char;
        }

  5. #5
    Registered User
    Join Date
    May 2002
    Posts
    23

    Thumbs up

    Thanks traveller. Exselent !!!
    Man don't know why but random access files gave me such a headache this last two days. I really blame the book am using.
    BTW thanks also for sugesting a book yesterday , i'll definatly give it a try.

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. Replies: 7
    Last Post: 09-26-2005, 06:09 PM
  2. Testing Random Number Generator
    By Roaring_Tiger in forum C Programming
    Replies: 7
    Last Post: 08-12-2005, 01:48 AM
  3. Random word problem
    By goron350 in forum C++ Programming
    Replies: 2
    Last Post: 05-14-2005, 04:44 PM
  4. Random Problem?
    By dizz in forum C++ Programming
    Replies: 4
    Last Post: 11-20-2002, 05:00 PM
  5. Random Access Files
    By Unregistered in forum C Programming
    Replies: 1
    Last Post: 08-29-2001, 09:06 AM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21