8-bit MicrocontrollersのトピックRe: 908GP32 - Address issue - pointer in C

908GP32 - Address issue - pointer in C

Stefano_RadioLa — Thu, 07 Jun 2007 17:18:11 GMT

Hi,
I am programmind 908GP32 with codewarrior usign C.
I have this question: i have a variable ( int not a pointer) and a data structure (array of int)
How can I do the following operation?

myvariable=address data structure

I need this because I am trying to implent a eeprom using flash with the driver descripted in an3040.

Do you have some suggestion?

Tx

--
Alban Edit: Changed title: Part number must be shown and clarified subject.

Message Edited by Alban on 2007-06-07 11:36 AM

Re: 908GP32 - Address issue - pointer in C

Alban — Thu, 07 Jun 2007 17:39:13 GMT

Hello,

& is the operator for address:

myvariable = &DataStruct;

Cheers,
Alban.

Re: 908GP32 - Address issue - pointer in C

thisobj — Thu, 07 Jun 2007 18:38:58 GMT

Hello Stefano,
You'll need to cast the address value to an "int" type to avoid a type mis-match error.
The following should work:

int myvariable;

int somearray[2];

void main(void) {

myvariable = (int)(&somearray);

// now to use "myvariable" as a pointer....

*( (int *)myvariable ) = 20; // places "20" at somearray[0];

}

Note that using pointers that are built by casting can lead to very difficult-to-find bugs. This usually occurs when incrementing or decrementing the pointer.

Frank