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From: Royston Vasey on 15 Mar 2010 01:26
I'm pushing along trying to learn some C using MCC18. Can someone please
tell me what the "&" before the variable "variable" does or means in the
code below? I'm finding it hard to find basic info like this in the
documentation I've found.

Is it AND? AND with what?

thanks



ee_read_byte(0x00, &cal_var); //initialise calibration variable from
eeprom

why the "&" -----------^




unsigned char ee_read_byte(unsigned char address, unsigned char *_data){
EEADR = address;
EECON1bits.CFGS = 0;
EECON1bits.EEPGD = 0;
EECON1bits.RD = 1;
*_data = EEDATA;
}


From: D Yuniskis on 15 Mar 2010 02:01
Royston Vasey wrote:
> I'm pushing along trying to learn some C using MCC18. Can someone please
> tell me what the "&" before the variable "variable" does or means in the
> code below? I'm finding it hard to find basic info like this in the
> documentation I've found.
>
> Is it AND? AND with what?
>
> ee_read_byte(0x00, &cal_var); //initialise calibration variable from
> eeprom
>
> why the "&" -----------^

read as: "address of" ...

> unsigned char ee_read_byte(unsigned char address, unsigned char *_data){

.... because this expects a pointer (i.e., an address) ------------^^^^

> EEADR = address;
> EECON1bits.CFGS = 0;
> EECON1bits.EEPGD = 0;
> EECON1bits.RD = 1;
> *_data = EEDATA;
> }
>
>
From: FreeRTOS info on 15 Mar 2010 02:53
On 15/03/2010 05:26, Royston Vasey wrote:
> I'm pushing along trying to learn some C using MCC18. Can someone please
> tell me what the "&" before the variable "variable" does or means in the
> code below? I'm finding it hard to find basic info like this in the
> documentation I've found.
>
> Is it AND? AND with what?
>
> thanks

<snip>

I don't think you can learn C very efficiently by posting questions to
ask what the syntax does. The normal and more efficient method is to
read a book. If that is too old fashioned, then try Google:

http://home.netcom.com/~tjensen/ptr/pointers.htm

--

Regards,
Richard.

+ http://www.FreeRTOS.org
Designed for Microcontrollers. More than 7000 downloads per month.

+ http://www.SafeRTOS.com
Certified by TÜV as meeting the requirements for safety related systems.



From: Hans-Bernhard Bröker on 15 Mar 2010 08:18
Royston Vasey wrote:

> I'm pushing along trying to learn some C using MCC18. Can someone please
> tell me what the "&" before the variable "variable" does or means in the
> code below? I'm finding it hard to find basic info like this in the
> documentation I've found.

That's because you've either been looking for the wrong kind of
documentation, or you've tackled this whole "learning a programming
language" task entirely the wrong way round.

What you actually need is introductory documentation of the C
programming language, a.k.a. a C textbook. The 2nd edition of the one
by Kernighan & Ritchie, who invented the language, is still among the best.

And the right order of things is not to jump in and try to understand
existing code by guessing what each letter in it means, but to actually
_learn_ the language first, then apply that knowledge to existing code.
From: Vladimir Vassilevsky on 15 Mar 2010 09:56


Royston Vasey wrote:
> I'm pushing along trying to learn some C using MCC18. Can someone please
> tell me what the "&" before the variable "variable" does or means in the
> code below?

This symbol means "the one with a tail should go down from the tree".

VLV
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