[ 2017-06-26 Moved to Tentatively NAD after 5 positive votes on c++std-lib. ]

[ 2017-02-23, Jens Maurer comments ]

This issue is NAD; the facility was redesigned with these considerations in mind before it went into the working draft.

If P0067R4 is applied consider how to parse hexadecimally:

to_chars(beg, end, 42, 16); 16 for hex

to_chars(beg, end, 4.2, true); true means hex

to_chars(beg, end, 4.2, chars_format::hex);

to_chars(beg, end, 4.2, chars_format::hex, 2);

That is: We have 3 different formats to specify hex depending on value types and whether to use precision. Which application programmer should remember this?

May be even worse (I am not sure):

to_chars(beg, end, 4.2, 16);

would silently convert 4.2 to 4 and

to_chars(beg, end, 4, chars_format::hex);

would silently convert 4 to 4.000000.

Proposed change: The various options should be harmonized, possibly by use of an extended enum approach, having the values: dec, hex, scientific, fixed, general with dec (new!) as default for integral values and general for floats