将数据从逗号分隔的文本文件加载到2D数组？

Question

I am trying to load data from a text file that looks like this:

161,77,88,255 0,44,33,11,111

etc. I have functions to manipulate it, and am ensured that the array is the correct size (which may still vary). Below is my attempt at implementation:

bool loadData(int **imgPix, string fileName) {

ifstream inputFile;

inputFile.open(fileName.c_str());

string tempLineRow; //The resulting line from the text file
string tempElementColumn; //The individual integer element 
int numberOfCols = 0;
int numberOfRows = 0;


if (!inputFile.is_open()) {
    return false;
}

imgPix = new int* [numberOfRows];

    while (getline(inputFile, tempLineRow, '\n')) {

        stringstream ss; 
        ss << tempLineRow; //Stringstream version of the line

        while (getline(ss, tempElementColumn, ',' )) {
            stringstream ss2; 
            ss2 << tempElementColumn;
            ss2 >> numberOfCols;

//Prob?         (**imgPix) = *(*(imgPix + numberOfRows) + numberOfCols);
            numberOfCols++;

        }

        numberOfRows++;

    }   

inputFile.close();
return true;

}

I've marked the line with the double pointer assignment with a comment, because I believe it be the source of my error, although there could be others. I'm not sure how to use the while loop structure I've implemented to iteratively update the 2D array.

Can anyone offer any assistance? Would be greatly appreciated!

Answer 1

Your code has several issues, mostly I guess because you did not fully understand how built-in arrays work in C++. The main issue here is that those cannot easily grow dynamically, there is no "resize" operation for those arrays (but you will need one here). So I suggest kindly that you try to rewrite your code using std::vector<int> and std::vector< std::vector<int> > , make sure you use of .resize when you store a new row or column and come back and ask again when you run into problems with this new implementation.

Answer 2

imgPix = new int* [numberOfRows]

Here numberOfRows = 0, so you don't allocate enough memory. You need to know dimensions of the array before you allocate the memory. And then you should also allocate a memory for each row in the array:

imgPix[currentRow] = new int [TotalCols];

For a 2-dimensional rectangular array, it would be more efficient to create 1-dimensional array of TotalRows*TotalCols elements, and then access it using formula A(row, col) = A[row*TotalCols + col] .

Answer 3

先前的答案是有效的，但是如果不需要连续内存，则在这种情况下，与std::vector相比， std::deque s可能是更好的选择，以避免大量的内存重新分配。