Read from a file C++

Question

Hi I want to read data from a VTK file into my C++ program. Here is how my files will typically look.

POINTS 2 double

1 2

Answer 1

You can use the ignore function to throw away lines of text that are not numbers. Use cin >> x to read a value x from the input file. If that fails, the failbit is set in the input stream, which you must clear. Then, ignore the whole line.

std::vector data;
while (!cin.eof())
{
    int x;
    if (cin >> x) {
        data.push_back(x);
        if (data.size() == 8)
        {
            // do whatever you need with the 8 numbers
            data.clear();
        }
    } else {
        cin.clear();
        cin.ignore(1000, '\n'); // assuming maximum line length less than 1000
    }
}

(This code assumes reading from cin, which is redirected to another input file)