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To: cs551@merlot.usc.edu
Subject: Re: how to obtain the address of the individual members of the structure...
Date: Sat, 06 Sep 2008 20:17:53 -0700
From: Bill Cheng <william@bourbon.usc.edu>

Someone wrote:

  > I want to write a function so that i can avoid writing the following
  > statements again and again
  > 
  > memcpy(msg_buf, &clientRequestMsg.msgType, 2);
  > memcpy(&msg_buf[2], &clientRequestMsg.offset, 4);
  > memcpy(&msg_buf[6], &clientRequestMsg.dataLen, 4);
  > 
  > Therefore, I wrote a function
  > 
  > void StructureToArray (char *ptr3, struct message* ptr4)
  > {
  >     memcpy(ptr3, (ptr4->msgType), 2);
  >     memcpy(ptr3[2],(ptr4->offset), 4);
  >     memcpy(ptr3[6], (ptr4->dataLen), 4);
  > }
  > 
  > now obviously, the above function wont work because (ptr4->msgType) will
  > give me the value of msgType and not its address.............so how do i
  > obtain the address of the individual members of the structure...........

You should use:

    &(ptr4->msgType).

Also, ptr3[2] has data type (char) and you need (char*).
So, you should use &ptr3[2].
--
Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>