title: What is the purpose of max_digits10 and how is it different from digits10?
body: <p>I am confused about what <code>max_digits10</code> represents. According to <a href="http://en.cppreference.com/w/cpp/types/numeric_limits/max_digits10" rel="noreferrer">its documentation</a>, it is 0 for all integral types. The formula for floating-point types for <code>max_digits10</code> looks similar to <code>int</code>'s <code>digits10</code>'s.</p>