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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: error: initializer element is not constant|
Date: Tue, 09 May 2017 08:11:48 -0700
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jak <please@nospam.tnx> writes:
[...]
> Ok ok. Bugs have also been put in the middle. The first time I wrote the 
> declaration in this way:
>
> char *Date = "01-01-80";
> char **Phrases[]
> {
>     &Date
> }
>
> and gcc gave me a lot of errors.

You have two simple syntax errors.  You need an "=" before the
initializer, and a semicolon after it.  With those changes, it compiles.

[...]

> But I still do not understand why the compiler does not allow me this:
>
> char *Date = NULL;
> char *Phrases[]
> {
>     "Date: ",
>     Date,
>     "\r\n"
> };
>
> In the end I'm just asking him to allocate space to write in an address 
> exactly as it happens when I write NULL instead of 'Date'.

The initializer for an object defined at file scope must consist only of
constant expressions.  The expression `Date` yields the value of a
variable, which obviously is not constant.  (A compiler might be able to
determine that the object hasn't been modified since its initialization,
but that doesn't make its name a constant expression.  Adding "const"
wouldn't help either; "const" means read-only, not constant.)

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"