Steganography MFC program problem...

Hi all,
I am trying to understand this piece of code. It is generating few
errors..
Well i have commented the section where i get the exception about i is
not defined. Whereas i is defined. But it keeps on giving me this
error. If i define i of for loop ..still i get the same error. And
also i dont understand what this statement"
message_file.open("message.steg",ios::out|ios::binary);" is doing. I
know its to open the file ..But there is no file by this name
anywhere. So is it created itself to store the message that i type in
or wt....

Any help would be highly appreciated...
thanks

 void encrypt_message::message_encryption()
{
    int no_of_chars = 8;
    //int i;
    TCHAR c;
    wofstream message_file;
    wifstream message_encrypt_file;
    message_file.open("message.steg",ios::out|ios::binary);

    for(int i = 0; i<_tcslen(message);i++)
        message_file.put(message[i]);
    message_file.close();
    get_key();
    sub_key();
    message_encrypt_file.open("message.steg", ios::in|ios::binary);
    message_file.open("encrypted.steg", ios::out|ios::binary);
    while(message_encrypt_file)
    {
        for(i=0; i<8; i++)
        {
            if(!message_encrypt_file)
                {
                       message[i]='\0';
                    break;
                }
                else
                {
                    message_encrypt_file.get(c);
                    message[i]=c;
                }

        }
        message[i]='\0'; // EXCEPTION HERE THAT i is used without
defining.
        convert_to_bits(message, message_in_bits);
        sub_message();
        _tcscpy_s(message_in_bits,encrypted_in_bits);
        convert_from_bits();
        for( i=0;i<no_of_chars;i++)
              message_file.put(message[i]);
    }
    message_file.close();
    message_encrypt_file.close();
    message_encrypt_file.open("encrypted_message.steg", ios::in|
ios::binary);
    i=0;
    while(message_encrypt_file)
    message_encrypt_file.open("encrypted_message.steg",ios::in|
ios::binary);
    i = 0;
    while(message_encrypt_file)
        message_encrypt_file.get(message[i++]);
    message[i]='\0';
    message_encrypt_file.close();
}