Computer Science Canada

Reading Specific Data in Files
Author:  NewHydrolisk [ Fri Jul 02, 2010 4:58 pm ]
Post subject:  Reading Specific Data in Files
Hello there. I am trying to create save and load functions that will write data to a file and read data from a file respectively. I am using Dev-C++, so my compiler would be MinGW. I think.

Specifically, the problem I have at hand is the data reading from the file. I have solved the saving portion of my task.

code:
void save() // game save
{
    ofstream charFile( "charFile.sav", ios::trunc | ios::binary ); // open output file stream for "charFile"
    if( charFile.is_open() == 1 )
    {
        charFile << "    destiny" << endl; // line 1
        charFile << destiny << endl; // line 2
        charFile << "    level" << endl; // l 3
        charFile << LVL << endl; // l 4
        charFile << "    experience" << endl; // l5
        charFile << EXP << endl; // l 6
        charFile << "    hitpoints" << endl; // l 7
        charFile << HP << endl; // l 8
        charFile << "    attack" << endl; // l 9
        charFile << ATK << endl; // l 10
        charFile << "    defence" << endl; // l 11
        charFile << DEF << endl; // l 12
         // l 13
        charFile.close();
    }
    else
    {
        error( "Could not save game." );
    }
}

void load() // game load
{
    ifstream charFile( "charFile.sav", ios::binary ); // open input fstream for "charFile"
    if( charFile.is_open() == 1 )
    {
       
    }
    else
    {
        error( "Could not load game. Previous game may not have been saved." );
    }
}


As you can see, the written binary file would have a total of 13 lines, with every line stating a comment or the comment's value. The saving portion works fine.

However, I am entirely at a loss as to how I would approach "loading" the same file into the program.

I know that I only need to load every even-numbered line from 2 to 12 and assign the appropriate variables the read values, but I simply do not know how to go about doing so.

-

If I do anything/say anything stupid, I'll try to fix it if you tell me. I've very little practical C++ experience, I'm still learning C++, and I'm more or less new to the forum.
Author:  Tony [ Sun Jul 04, 2010 12:54 pm ]
Post subject:  RE:Reading Specific Data in Files
You are opening the files for binary input/output, but your code suggests that you actually want to be in the text mode (there are no "2nd line" in binary mode, there's only "42 bytes in, here's a stream of bits").

http://www.cplusplus.com/doc/tutorial/files/
Author:  NewHydrolisk [ Sun Jul 04, 2010 2:42 pm ]
Post subject:  Re: Reading Specific Data in Files
oops okay I got/changed it now.

c++:
void load() // game load
{
    ifstream charFile( "charFile.sav" ); // open input fstream for "charFile"
    if( charFile.is_open() == 1 )
    {
        string line;
        for( int i = 0; i != 13; i++ )
        {
            getline( charFile, line );
            if( i % 2 == 1 )
            {
                cout << line << endl;
            }
        }
        charFile.close();
    }
    else
    {
        error( "Could not load game. Previous game may not have been saved." );
    }
}


Here's what I have now. It works perfectly as intended. However, I'm just curious if there is a more efficient way of reading the file, since the program would read the unnecessary header lines too.

I don't think I can use seekg() because the odd lines carry values that might vary in number of digits.

:


You can syndicate this boards posts using the file backend.php or view the topic map using sitemap.php.

Terms of Use | Privacy Policy