** an optional digit string. If the digit string is omitted, the
** precision is taken as zero. This gives the minimum number of
** digits to appear for d, i, o, u, x, and X conversions, the number
** of digits to appear after the decimal-point for e, E, and f
** conversions, the maximum number of significant digits for g and G
** conversions, or the maximum number of characters to be printed
** an optional digit string. If the digit string is omitted, the
** precision is taken as zero. This gives the minimum number of
** digits to appear for d, i, o, u, x, and X conversions, the number
** of digits to appear after the decimal-point for e, E, and f
** conversions, the maximum number of significant digits for g and G
** conversions, or the maximum number of characters to be printed