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* gdb.texinfo (Output): Spell out which features of C's printf are

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not supported by GDB's printf.
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Eli Zaretskii 2007-09-15 08:54:26 +00:00
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5
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@ -1,3 +1,8 @@
2007-09-15 Eli Zaretskii <eliz@gnu.org>
* gdb.texinfo (Output): Spell out which features of C's printf are
not supported by GDB's printf.
2007-09-04 Daniel Jacobowitz <dan@codesourcery.com>
Jim Blandy <jimb@codesourcery.com>

67
gdb/doc/gdb.texinfo
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@ -16418,30 +16418,69 @@ the same formats as for @code{print}. @xref{Output Formats,,Output
Formats}, for more information.
@kindex printf
@item printf @var{string}, @var{expressions}@dots{}
Print the values of the @var{expressions} under the control of
@var{string}. The @var{expressions} are separated by commas and may be
either numbers or pointers. Their values are printed as specified by
@var{string}, exactly as if your program were to execute the C
subroutine
@c FIXME: the above implies that at least all ANSI C formats are
@c supported, but it isn't true: %E and %G don't work (or so it seems).
@c Either this is a bug, or the manual should document what formats are
@c supported.
@item printf @var{template}, @var{expressions}@dots{}
Print the values of one or more @var{expressions} under the control of
the string @var{template}. To print several values, make
@var{expressions} be a comma-separated list of individual expressions,
which may be either numbers or pointers. Their values are printed as
specified by @var{template}, exactly as a C program would do by
executing the code below:
@smallexample
printf (@var{string}, @var{expressions}@dots{});
printf (@var{template}, @var{expressions}@dots{});
@end smallexample
As in @code{C} @code{printf}, ordinary characters in @var{template}
are printed verbatim, while @dfn{conversion specification} introduced
by the @samp{%} character cause subsequent @var{expressions} to be
evaluated, their values converted and formatted according to type and
style information encoded in the conversion specifications, and then
printed.
For example, you can print two values in hex like this:
@smallexample
printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo
@end smallexample
The only backslash-escape sequences that you can use in the format
string are the simple ones that consist of backslash followed by a
letter.
@code{printf} supports all the standard @code{C} conversion
specifications, including the flags and modifiers between the @samp{%}
character and the conversion letter, with the following exceptions:
@itemize @bullet
@item
The argument-ordering modifiers, such as @samp{2$}, are not supported.
@item
The modifier @samp{*} is not supported for specifying precision or
width.
@item
The @samp{'} flag (for separation of digits into groups according to
@code{LC_NUMERIC'}) is not supported.
@item
The type modifiers @samp{hh}, @samp{j}, @samp{t}, and @samp{z} are not
supported.
@item
The conversion letter @samp{n} (as in @samp{%n}) is not supported.
@item
The conversion letters @samp{a} and @samp{A} are not supported.
@end itemize
@noindent
Note that the @samp{ll} type modifier is supported only if the
underlying @code{C} implementation used to build @value{GDBN} supports
the @code{long long int} type, and the @samp{L} type modifier is
supported only if @code{long double} type is available.
As in @code{C}, @code{printf} supports simple backslash-escape
sequences, such as @code{\n}, @samp{\t}, @samp{\\}, @samp{\"},
@samp{\a}, and @samp{\f}, that consist of backslash followed by a
single character. Octal and hexadecimal escape sequences are not
supported.
@end table
@node Interpreters