Bug with replacing elements in 2D Vector

[kcwijaya]

Hi! I have a 2D Vector defined as vector

    void initGridFromInput(vector <vector <int> > & sudokuGrid){
    cout << endl << "Enter one row at a time without spaces between characters." << endl;            string line;
    for (int i = 0; i < ROWS; i++){
        while (true){
            cout << "Enter row: ";
            cin >> line;
            if (line.length() == COLS) break;
            else {
                cout << "The row must have 9 characters." << endl;
            }
        }
        vector <int> rowVector(COLS);
        for (int j = 0; j < COLS; j++){
            cout << "Line[j] = " << line[j] << endl; // Find j'th character of line
            cout << "Before: " << rowVector.at(j) << endl; // jth element of vector before
            rowVector.at(j) = line[j];
            cout << "After: " << rowVector.at(j)<< endl; // jth element of vector after
        }
        sudokuGrid.at(i) = rowVector;
        cout << endl;
    }
    
}

For some reason, the cout statements print out:

Enter row: 763418259
Line[j] = 7
Before: 0
After: 55
Line[j] = 6
Before: 0
After: 54

and this continues...

What is wrong with my code? I am used to using the C++ libraries given by Stanford so using the STD version of vector is taking some getting used to.

[MiiNiPaa]

character '1' does not equal to integer 1
try this to understand:

int x = '7';
std::cout << x;

[keskiverto]

line[j] is a char. The '7' is a character that looks like, well, seven. However, that printable character has integer value too (just like 'a' does too). That seems to be 55. (See ASCII, and other character encodings.)