confused with Handle pointer

[wolf99]

Hi Folks

Pointers in C is something I always end up confusing myself with...

I have a function that is passed a pointer to a handle. this function should then pass that pointer on to a sub-function.

int txSerial (HANDLE *hComm) {
  // Do some stuff using *hComm here.
  // EG. 
  if (*hComm == INVALID_HANDLE_VALUE) {
    printf("Comm port returned an invalid handle\n");
    return 1;
  }
  return 0;
}

int txSPI (HANDLE *hComm) {
  return (txSerial(hComm));  //<<--- CONFUSED HERE.
}

int main (void) {
  HANDLE hComm1;
  int x;
  // Assign a handle to hComm1.

  x = txSPI(&hComm1);
  return x;
}

My confusion is where I call the sub-function txSerial().
Should I be passing *hComm or hComm ???
Got my thinking all knotted up here, help much appreciated, Thanks

[wolf99]

Im thinking it should be hComm not *hComm

As to pass it *hComm would be to pass the data stored at the location pointed to by hComm (ie the HANDLE itself) rather than passing the address of that location....

Is that correct or have I got it arse-ways?

[Atheist]

You're right.
Since hComm in txSPI is already a pointer to a handle, you should pass it as-is to txSerial.

*hComm would dereference the pointer, leaving you with the handle it points to.

[wolf99]

Thanks Athiest