[Main]
Title=Other Directives
Index=#ident

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The <CODE>#ident</CODE> directive takes one argument, a string constant.  On
some systems, that string constant is copied into a special segment of
the object file.  On other systems, the directive is ignored.
<BR><BR>
This directive is not part of the C standard, but it is not an official
GNU extension either.  We believe it came from System V.
<BR><BR>
The <CODE>#sccs</CODE> directive is recognized, because it appears in the
header files of some systems.  It is a very old, obscure, extension
which we did not invent, and we have been unable to find any
documentation of what it should do, so GCC simply ignores it.
<BR><BR>
The <U>null directive</U> consists of a <CODE>#</CODE> followed by a newline,
with only whitespace (including comments) in between.  A null directive
is understood as a preprocessing directive but has no effect on the
preprocessor output.  The primary significance of the existence of the
null directive is that an input line consisting of just a <CODE>#</CODE> will
produce no output, rather than a line of output containing just a
<CODE>#</CODE>.  Supposedly some old C programs contain such lines.
