======================= Cover sheet starts here ========================

                    Document Number:  WG14 N___/X3J11 __-___

                               C9X Revision Proposal
                               =====================

 Title:              printf function pointers
 Author:             David R. Tribble
 Author Affiliation: Self
 Postal Address:     6004 Cave River Dr.
                     Plano, TX 75093-6951
                     USA
 E-mail Address:     dtribble@technologist.com
                     david.tribble@beasys.com
                     dtribble@flash.net
 Web:                http://www.flash.net/~dtribble
 Telephone Number:   +1 972 738 6125, 15:00-00:00 UT
                     +1 972 964 1720, 00:00-03:00 UT
 Fax Number:         +1 972 738 6111
 Sponsor:            ________________________________________
 Date:               1999-02-08
 Revision:           2
 Proposal Category:
    __ Editorial change/non-normative contribution
    __ Correction
    X_ New feature
    __ Addition to obsolescent feature list
    __ Addition to Future Directions
    __ Other (please specify)  _____________________________
 Area of Standard Affected:
    __ Environment
    __ Language
    __ Preprocessor
    X_ Library
       __ Macro/typedef/tag name
       X_ Function
       __ Header
    __ Other (please specify)  _____________________________
 Prior Art:          None known.
 Target Audience:    Users of printf() and scanf()
 Related Documents (if any): None
 Proposal Attached: X_ Yes __ No, but what's your interest?
 Abstract:           The addition of a format specifier for writing and
    reading function pointer values.

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 DESCRIPTION

 This proposal describes the addition of a printf/scanf format
 specifier to be used for writing and reading function pointer values.
 This would be especially useful for debugging.

 This need arises in C because function pointers might not be
 convertible to (data) pointers to void (see 6.2.5p27).

 PROPOSAL

 (Section numbers are based on the C9X draft WG14/N843 dated
 1998-08-03.)

 Change 7.19.6.1p7 by adding the bracketed text:

  j  Specifies that a following d, i, o, u, x, or X conversion
     specifier applies to an intmax_t or uintmax_t argument; or
     that a following n conversion specifier applies to a pointer
     to an intmax_t argument{; or that a following p conversion
     specifier applies to a pointer to a function argument}.

 Change 7.19.6.1p8 by adding the bracketed text:

  p  The argument shall be a pointer to void{, or if the format
     specifier was preceded by a j modifier, the argument shall
     be a pointer to a function of type void(void)}.  The value
     of the pointer is converted to a sequence of printable
     characters, in an implementation-defined manner.

 Change 7.19.6.2p11 by adding the bracketed text:

  j  Specifies that a following d, i, o, u, x, X, or n conversion
     specifier applies to an argument with type intmax_t or
     uintmax_t{; or that a following p conversion specifier applies
     to an argument with pointer to function type}.

 Change 7.19.6.2p12 by adding the bracketed text:

  p  Matches an implementation-defined set of sequences, which
     should be the same as the set of sequences that may be
     produced by the %p {or %jp} conversion of the fprintf function.
     The corresponding argument shall be a pointer to a pointer to
     void{, or if the format specifier was preceded by a j modifier,
     the argument shall be a pointer to a pointer to a function of
     type void(void)}.  The interpretation of the input item is
     implementation-defined.  If the input item is a value converted
     earlier during the same program execution, the pointer that
     results shall compare equal to that value; otherwise the
     behavior of the %p {or %jp} conversion is undefined.

 Note: It is assumed that pointer to function types may have
 different representations than other (data) pointer types; see
 6.2.5p27.

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