Is std::to_string guaranteed to include a decimal point when converting floating point values?

With the below code,

int main() {
    for(;;) {
        float d;
        cin >> d;
        cout << std::to_string(d) << endl;
    }
}

to_string seems to always return a string containing a decimal point followed by six digits. Is this behavior guaranteed (excluding nan and infinity)?

According to cplusplus.com , "as many digits are written as needed to represent the integral part, followed by the decimal-point character and six decimal digits".