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From: Philip Cheng <cheng@PCIgeomatics.com>
Message-Id: <200203041433.g24EX6b32257@PCIgeomatics.com>
Subject: Re: Use of typeof
To: ke-gcc@retriever.dyndns.org (Kevin Bailey)
Date: Mon, 04 Mar 2002 06:36:00 -0000
Cc: gcc-help@gcc.gnu.org
In-Reply-To: <20020302110414.S28462@hawk.ind.alcatel.com> from "Kevin Bailey" at Mar 02, 2002 11:04:14 AM
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Kevin:

If you look at 

http://gcc.gnu.org/onlinedocs/gcc-3.0.3/gcc_5.html#SEC74

you will find that typeof is gcc extension. 

There are two ways of writing the argument to typeof: with an expression 
or with a type. Here is an example with an expression: 

   typeof (x[0](1))

This assumes that x is an array of pointers to functions; the type described 
is that of the values of the functions. 

Here is an example with a typename as the argument: 

   typeof (int *)

Seems typeof does not work with the 2nd method.   Maybe it is a gcc bug?

Philip 

> 
> There is no such thing as typeof in C.
> 
> However, there is in C++ so either rename your file to test.cc
> or compile with -xc++.
> 
> On Fri, Mar 01, 2002 at 11:01:18AM -0500, Philip Cheng wrote:
> > I would like to use typeof to determine the type of a variable.  
> > However, I keep getting the error when I try to compile the program.
> > 
> >   test.c: In function `main':
> >   test.c:8: parse error before "typeof"
> > 
> > Anyone knows how can I solve the problem?  Thanks in advance for your help.
> > 
> > Philip
> > 
> > 
> > Here is my test program:
> > 
> > #include <stdio.h>
> > 
> > main()
> > {
> >         double  dftest;
> >         dftest = 1.0;
> > 
> >         if (__builtin_types_compatible_p (typeof (dftest), double)) 
> >             printf("It is double\n");
> > } 
>