Ryū Printf is a new algorithm to convert floating-point numbers to decimal strings according to the \texttt{printf} \texttt{%f}, \texttt{%e}, and \texttt{%g} formats: \texttt{%f} generates `full' output (integer part of the input, dot, configurable number of digits), \texttt{%e} generates scientific output (one leading digit, dot, configurable number of digits, exponent), and \texttt{%g} generates the shorter of the two. Ryū Printf is based on the Ryū algorithm, which converts binary floating-point numbers to the shortest equivalent decimal floating-point representation. We provide quantitative evidence that Ryū Printf is between $3.8$ and $55$ times faster than existing \texttt{printf} implementations.

Furthermore, we show that both Ryū and Ryū Printf generalize to arbitrary number bases. This finding implies the existence of a fast algorithm to convert from base-10 to base-2, as long as the maximum precision of the input is known a priori.