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In article <4hmslc$b35@solutions.solon.com>
thomas@eel.rdc.toshiba.co.jp (Arun M. Thomas) writes:

AMT: With respect to the first line in this paragraph then, how does
one declare  
AMT: a variable without also defining it?  A statement like:
AMT: 
AMT: 	int i;
AMT: 
AMT: both declares and creates a tentative definition of the variable if I am
AMT: understanding correctly.  (I can't think of a case in which it
will actually be 
AMT: necessary to declare without defining a variable, but I'm asking
to find out if 
AMT: it is possible.  If there is a situation in which it would be
useful to declare 
AMT: without defining, I would appreciate an example.)
AMT: 
AMT: >From the discussion preceding the section included above, I
gathered that  
AMT: within a function, a statement like the above (i.e. "int i;") is
in fact a  
AMT: bare declaration, with no default value assigned to it.  If this
understanding 
AMT: is incorrect, please let me know :)

I suspect your basic problem is that you think `define a variable'
means `giving this variable a value'. This was not the sense in which
it was being used in this thread so far.

In this thread, people were trying to distinguish two different types
of declaration: one that just informs that the variable has been
`created' somewhere (with or without initialization), and the other
instructs the compiler to create the variable. It is this latter kind
of declaration which is called `definition'.

So, if you write `extern int i;' in any context whatsoever, i is
declared but not defined. It tells the compiler that a static duration
variable i exists. (It turns out that such a variable cannot be
uninitialized.) Note that `extern int i;' itself does not create the
object. 

`extern int i = 12;' is a definition. It creates i and initializes it
to 12. (This declaration is invalid inside a block.)

`int i;' inside a block is a definition. It however does not
initialize the object.

`int i;' at file scope is a tentative definition, which in itself
doesn't reserve space: but guarantees that space will be reserved (and
initialized) in the translation unit.

Cheers
Tanmoy
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