Function float_to_text

src/common/cvt.cpp:249–388

static void float_to_text(const dsc* from, dsc* to, Callbacks* cb)
{
/**************************************
 *
 *      f l o a t _ t o _ t e x t
 *
 **************************************
 *
 * Functional description
 *      Convert an arbitrary floating type number to text.
 *      To avoid messiness, convert first into a temp (fixed) then
 *      move to the destination.
 *      Never print more digits than the source type can actually
 *      provide: instead pad the output with blanks on the right if
 *      needed.
 *
 **************************************/
	double d;
	char temp[] = "-1.234567890123456E-300";

	const int to_len = DSC_string_length(to); // length of destination
	const int width = MIN(to_len, (int) sizeof(temp) - 1); // minimum width to print

	int precision;
	if (dtype_double == from->dsc_dtype)
	{
		precision = 16;			// minimum significant digits in a double
		d = *(double*) from->dsc_address;
	}
	else
	{
		fb_assert(dtype_real == from->dsc_dtype);
		precision = 8;			// minimum significant digits in a float
		d = (double) *(float*) from->dsc_address;
	}

	// If this is a double with non-zero scale, then it is an old-style
	// NUMERIC(15, -scale): print it in fixed format with -scale digits
	// to the right of the ".".

	// CVC: Here sprintf was given an extra space in the two formatting
	// masks used below, "%- #*.*f" and "%- #*.*g" but certainly with positive
	// quantities and CAST it yields an annoying leading space.
	// However, by getting rid of the space you get in dialect 1:
	// cast(17/13 as char(5))  => 1.308
	// cast(-17/13 as char(5)) => -1.31
	// Since this is inconsistent with dialect 3, see workaround at the tail
	// of this function.

	int chars_printed;			// number of characters printed
	if ((dtype_double == from->dsc_dtype) && (from->dsc_scale < 0))
	{
		chars_printed = fb_utils::snprintf(temp, sizeof(temp), "%- #*.*f", width, -from->dsc_scale, d);
		if (chars_printed <= 0 || chars_printed > width)
			chars_printed = -1;
	}
	else
		chars_printed = -1;