From mboxrd@z Thu Jan  1 00:00:00 1970
From: dexen deVries <dexen.devries@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Date: Thu,  8 Sep 2011 11:57:07 +0200
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Subject: Re: [9fans] C question - completely OT,
	but I'd like to know the answer
Topicbox-Message-UUID: 1bacee28-ead7-11e9-9d60-3106f5b1d025

On Thursday 08 of September 2011 11:41:05 Winston Kodogo wrote:
> (...)
> I'm puzzled as to why the line "int nigel =3D 1;" is syntactically OK,
> and although it seems to have declared the variable "nigel" - else the
> following code would fail to compile - has failed to give it the
> initial value of 1, as requested.

consider the `switch' statement a switchboard that jumps to one of the=20
`case's.

nigel is not getting initialized because this code path is not executed -- =
as=20
it is not part of any `case' taken by the switch.=20

an `automatic' (non-static) variable is initialized by a piece of code, the=
=20
code gets executed whenever flow of control reaches that particular place.

a static variable (`static int inigel =3D 1') is initialized by static data=
,=20
before any code gets executed -- and only once. static will do what you=20
expect.

this is why you can place a static variable outside of any function and it=
=20
still gets initialized.

both kinds have their uses, in different situations.

for reference:

for (int i =3D 0; i < 8; ++i) {
  int nigel =3D 1; // this emits some code that gets executed for every loo=
p and=20
resets the var to `1'
  printf("nigel: %d,", nigel);
  ++nigel;
}

will print: nigel: 1,nigel: 1,nigel: 1, ...

on the other hand:=20

for (int i =3D 0; i < 8; ++i) {
  static int nigel =3D 1; // this var is initialized just once before main(=
)=20
begins and doesn't reset
  printf("nigel: %d,", nigel);
  ++nigel;
}

will print: nigel: 1,nigel: 2,nigel: 3, ...


=2D-=20
dexen deVries

[[[=E2=86=93][=E2=86=92]]]

=46or example, if the first thing in the file is:
   <?kzy irefvba=3D"1.0" rapbqvat=3D"ebg13"?>
an XML parser will recognize that the document is stored in the traditional=
=20
ROT13 encoding.

(( Joe English, http://www.flightlab.com/~joe/sgml/faq-not.txt ))