How to output float to cout without scientific notation or trailing zeros?

Question

What is the most elegant way to output a floating point number in C++ with no scientific notation or trailing zeros?

Answer 1

If string manipulating doesn't hurt your eyes:

std::string fixedfloat(float x)
{
    std::ostringstream ss;
    ss << std::fixed << std::setprecision(std::cout.precision()) << x;
    std::string str = ss.str();
    return str.substr(0, str.find_last_not_of('0') + 1);
}

int main()
{
    float b = 0.1f;

    std::cout << std::setprecision(6) << fixedfloat(b);
}

or

class fixedfloat
{
public:
    fixedfloat(float x) : x(x) {}
    float value() const { return x; }

private:
    float x;
};

ostream &operator<<(ostream &out, const fixedfloat &f)
{
    ostringstream ss;
    ss << fixed << setprecision(out.precision()) << f.value();
    string str = ss.str();
    out << str.substr(0, str.find_last_not_of('0') + 1);
    return out;
}

int main()
{
    float b = 0.1f;

    cout << setprecision(6) << fixedfloat(b);
}