I am trying to pass a char * to a function where upon some processing of
data the value of the pointer is set to the address of an array of char
embedded in a struct.  This is on an embedded system, so I have limited
debug capability.

code fragment:(s):

    unsigned char *robstr;

    do // Get ack message on COM0
    {
       status = GetMsgCOM0( &robstr );
       if( ack_time >= 300 ) timeout = 1;
    }while(( status == -1 ) && ( timeout == 0 ));

S_BUFFER com0_msg_buf;

char GetMsgCOM0( char *buffer )
{

    // process...
    // if success
           *buffer = com0_msg_buf.storage;
    return;

where the struct is:

struct small_buffer_type
{
  unsigned char storage[256];   /* Buffer storage array */
  unsigned char size;
  unsigned char in;   /* Input index */
  unsigned char out;  /* Output index */
  unsigned char over; /* Buffer overflow flag */

typedef struct small_buffer_type S_BUFFER;

At the point where GetMsgCOM0 is entered, I sent the value of buffer out the
serial port.  It had the address of robstr as its value, which seems right.
The problem comes when I try to assign the value of &com0_msg_buf.storage to
robstr through buffer.

I don't want to alter the character string pointed to by
com0_msg_buf.storage.  I just want to access it as though it were an array
without having  com0_msg_buf be a global variable.

Do I need to use char ** to pass a pointer to a pointer to char, so I can
assign the address of the pointer?

Please help!
--
Robert Allen
Development Engineer
Electrosonic Systems, Inc.

On Mon, 19 Jan 1998 16:19:22 -0600, Robert Allen

[ much snippage ]

There are at least two errors.  First, your function definition expects
a pointer to character, yet you are passing in the address of the
pointer of a character.  Second, you are assigning something of type
array of char (which decays to a pointer to char) to a something of type
char.

Try redeclaring your function to expect a pointer to a pointer to char:

char GetMsgCOM0( char **buffer )
{
  /* ... */
           *buffer = com0_msg_buf.storage;
    return;

--

http://www.cs.wustl.edu/~jxh/        Washington University in Saint Louis