从C ++中的文件加载到2D数组中

Question

I am having trouble reading numbers from a file into a 2d array in c++. It reads the first row just fine but the rest of the rows are populated with 0's. I have no idea what I'm doing wrong.

#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    int myarray[20][20];

    int totRow = 20, totCol = 20, number, product, topProduct = 0, row, col, count;
    char element[4];

    ifstream file;

    file.open( "c:\\2020.txt" );

    if( !file )
    {
        cout << "problem";
        cin.clear();
        cin.ignore(255, '\n');
        cin.get();

        return 0;
    }

    while( file.good())
    {
        for( row = 0; row < totRow; row++ )
        {
            for( col = 0; col < totCol; col++ )
            {
                file.get( element, 4 );
                number = atoi( element );
                myarray[row][col] = number;
                cout << myarray[row][col] << " ";
            }
            cout << endl;

        }
        file.close();
    } 

Answer 1

If there are only numbers in your file, you can just read them with the >> operator. Change your inner loop to:

for( col = 0; col < totCol; col++ )
{
    file >> myarray[row][col];
    cout << myarray[row][col] << " ";
}

The problem with file.get() is, it doesn't read beyond newline \\n . See: std::basic_istream::get

Answer 2

You're closing the file inside the while loop:

while( file.good())
    {
        for( row = 0; row < totRow; row++ )
        {
            for( col = 0; col < totCol; col++ )
            {
                file.get( element, 4 );
                number = atoi( element );
                myarray[row][col] = number;
                cout << myarray[row][col] << " ";
            }
            cout << endl;

        }
        file.close();   // <------ HERE
    } // end of while loop is here

You obviously can't read from a closed stream. Now, because you're trying to read all the data in the first iteration of the while loop, this doesn't seem to be your immediate problem. Note however, that the stream can still be good() even after you've read all the meaningful data (for example if there's a traling new-line character) and in that case, you'll enter the loop for the second time. That's a bug.