Path: utzoo!mnetor!tmsoft!torsqnt!hybrid!scifi!bywater!uunet!taumet!steve
From: steve@taumet.com (Stephen Clamage)
Newsgroups: comp.lang.c
Subject: Re: initializing to expressions
Message-ID: <598@taumet.com>
Date: 9 Feb 91 18:16:46 GMT
References: <91039.144030BRL102@psuvm.psu.edu>
Organization: Taumetric Corporation, San Diego
Lines: 20

BRL102@psuvm.psu.edu (Ben Liblit) writes:

>I want to initialize an array [statically] with values that are constant,
>but are in the form of expressions.  For example,

>   double  value[ 2 ] = { sqrt( 2 ) / 2, cos ( sqrt( 5 ) ) };

>Is there any way to accomplish this?

In C, static initializers may not contain function calls.  sqrt and cos
are part of the run-time library, not built-in to the language.

C++, however, allows general expressions to initialize static variables.
The compiler collects non-constant expressions into a compiler-generated
initialization routine, then calls the routine before any user code in
the main program.  This is in fact run-time, rather than compile-time,
initialization, but it allows the convenient notation you want.
-- 

Steve Clamage, TauMetric Corp, steve@taumet.com