-----Original Message----- From: Ben Warren [mailto:biggerbadderben@gmail.com] Sent: Thursday, April 09, 2009 2:33 AM To: Premi, Sanjeev Cc: Timur Tabi; Jerry Van Baren; U-Boot-Users ML; Kumar Gala Subject: Re: [U-Boot] use of C99
Premi, Sanjeev wrote:
-----Original Message----- From: u-boot-bounces@lists.denx.de [mailto:u-boot-bounces@lists.denx.de] On Behalf Of Timur Tabi Sent: Thursday, April 09, 2009 1:55 AM To: Jerry Van Baren Cc: U-Boot-Users ML; Kumar Gala Subject: Re: [U-Boot] use of C99
On Wed, Apr 8, 2009 at 2:46 PM, Jerry Van Baren gerald.vanbaren@ge.com wrote:
ACK. I don't expect to see variables spring into life in
the middle of
nowhere.
I don't see what's wrong with that. The advantage is that the variable is close to where it's being used, so that you can see the context more easily.
If I'm not confused, I've seen block-local u-boot
variables, has the
advantages of being more distinctive and limits the
lifetime of the
variable.
I don't see what the value is of limiting the lifetime of the variable. The compiler isn't going to use that as a hint, anyway. It's just going to use this for syntax checking. If you define and initialize a variable at the top of the function, but
don't use that
variable until a hundred lines later, the compiler is going to initialize the variable when it's first used, not when the
function is
first entered. Chances are it's not even going to define
stack space
for it.
One of the biggest problem is uncontrolled variable definitions that gets even nasty when variables have same names with different types; though under different set of #ifdefs. Quite possible for commonly used variable names - i, ptr, tmp, etc.
I'm showing extreme ignorance here, but does C99 let you do this?
for (int i = 0; i < x ; i++) ?
That's much better contained than declaring in a ifdef.
Doing a lot of C++ has rotted my brain, but this is one thing I like.
I love C++; still avoid declare as you go. Iterators (as you mention above) are only exception.
~sanjeev
regards, Ben