From yechiel Mon Jun  2 01:24:34 2003
Subject: Re: thank you
To: <a student>
Date: Mon, 2 Jun 2003 01:24:34 +0300 (IDT)

> Hello!
> I was your student when studied matam a time ago.
> Thank you for -ansi -Wall -pedantic.
> Now (in structure of OS) this line saved me and my partners many days of
> debugging. When we execute our program there were many mistakes and
> strange things  we couldn't find. After compiling with the Line we solved
> all our problems.  Without this flags gcc didn't get us message that we
> forgot the word "case" inside "switch"!
> BIG THANKS.

I am truly happy for you, and I take it as a complement
that you cared to tell me about it.

Is it o.k. with you that I put your e-mail (without your names)
on my Web-page, in order to encourage other students to do so?
No hard feelings if you do not like the idea, and I won't do that
unless I get an explicit consent from you.

> One small question is left: when we initialize array like "int
> arr[10]={0}" are all cells initialized or only the first one?
> If you have time to answer->please do.

The _basic_ rules for array initialization are as follows:
   Given the definition

       T-type  arr[SIZE] = { val-0, val-1, /***  some more  ***/, val-k};

   First, in C, all val-i expressions must be constant-expressions.
   If SIZE < k+1 this is a syntax error (too many values).
   If there is an i  0 <= i <= k  s.t. the type of val-i
     _cannot_ be converted to the type "T-type"
     it is a (semantical) compile-time error.
   Then, for every i  0 <= i <= k arr[i] is initialized
     as if there was a statement  arr[i] = val-i;
     and for every i  k < i < SIZE as if there was arr[i] = 0;
     In C++, the latter case the initialization is by the default Ctor.
   The rules are the same for structs (in C) where "T-type" may vary.
   The rules are the same for classes (in C++) where all non-static
     data-members are public (and a few more restrictions).
   The type "T-type" _can_ be a struct/class/array type by itself.

I am sure you can draw the conclusion ;->

> Regards,
> <students>

Enjoy
Yechiel
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	Yechiel M. Kimchi		    yechiel@someserver.someplace
	Faculty Comp. Sc.		    The Technion, Haifa, 32000 IL
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