Thread: C++ strcuts and arrays

  1. #1
    Registered User
    Join Date
    May 2007

    C++ strcuts and arrays

    In the following code I am trying to resize the array at the correct place, my teacher said to ask for input for one item of the struct first then use a temp variable and I can't figure this out. thanks.

    if( if-else
            cout<<"Sorry, the file could not be opened."<<endl;
            while(!infile.eof())//this while loop resizes the vector and inputs the names from the file until the file ends
            {//begin while
                int temp = recordList[recordList.length()].sku;
                if(temp != infile.eof())//this if
                {//begin if
                    recordList.resize(recordList.length() + 1);
                }//end if
            }//end while
        }//end if-else

  2. #2
    Registered User
    Join Date
    May 2007
    int temp = recordList[recordList.length()].sku;
    First of all, where is everybody getting the length() method from on these containers? Is that standard? I've never seen it in any reference (including TC++PL). I'm pretty sure that size() is what you want. Second, that is fundamentally incorrect. Because indices start at 0, the recordList.size() element will always be out of bounds. Think about it. I think what your teacher wants you to do, rather than using the resize() method, is to use a temporary structure in tandem with push_back, like this:

    //First, create a temporary structure to hold input
    //I don't know what type recordList holds, so I'll guess
    Record input;
    //You should consider not basing your loop on infile.eof(), it can be squirrely
    //Read the FAQ on feof()
    while(!infile.eof())//this while loop resizes the vector and inputs the names from the file until the file ends
            {//begin while   
                infile >>input.sku;
                if(input.sku != EOF) //This is probably still wrong, but it's closer.
                {//begin if <--- WHY THESE COMMENTS? IS INDENTATION NOT ENOUGH?
                    infile.ignore(2,'\n'); //THIS LINE REALLY ISN'T SAFE
                    getline(infile, input.artist);
                    getline(infile, input.album);
                    infile >>input.quantity >>input.price;
    Hope this helps.
    Last edited by UMR_Student; 05-15-2007 at 09:59 PM.

  3. #3
    Hurry Slowly vart's Avatar
    Join Date
    Oct 2006
    Rishon LeZion, Israel
    to avoid using ignore you can read ALL the input using getline
    and then - if needed - extract the data from the readed string using stringstream - there is a lot of samples on the board - how to do this
    All problems in computer science can be solved by another level of indirection,
    except for the problem of too many layers of indirection.
    David J. Wheeler

Popular pages Recent additions subscribe to a feed