在C ++中将字符串转换为double

Question

I've made a function that receives a line and a delimiter, separates the line and returns a vector of floats (like the split function in java). This is the function:

vector<float> extractNumbers(string line, char delimiter) {
    vector<float> a;
    float f;
    string forNow = "";
    for (unsigned int i = 0; i < line.size(); i++) {
        if (line.at(i) == delimeter) {
            f = ::atof(forNow.c_str());
            cout << ::atof(forNow.c_str()) << endl;
            a.push_back(f);
            forNow = "";
        } else {
            forNow += line.at(i);
        }
    }
    f = ::atof(forNow.c_str());
    cout << f << endl;
    a.push_back(f);
    return a;
}

This is the text file I'm trying it with:

3 3
1 1 1
1 2 1
1 1 1

I call this function: vector<float> floatLine = extractNumbers(line, ' '); When I try to print forNow parameter I receive the numbers just like in the text, but when I print f or ::atof(forNow.c_str()) I receive a 0 instead of the first 3 in the first line. Any thoughts?

Answer 1

Just if you don't know about such convenient way of interaction with files. You can use them like this:

float a, b;
float c, d, e;
float f, g, h;
fstream file("data.dat", ios::in);
if (file) {
    file >> a >> b;
    file >> c >> d >> e;
    file >> f >> g >> h;
    file.close();
}