How to open panel in previous position?

[PC Programmer]

Part II

Retrieve Position Code

   int LastPos;
    char PanelLeft[10];
    char PanelTop[10];
    int PanelLastTop, PanelLastLeft;
    char buff[50];
    int  Status;
    char *ErrMsg;

 Status = RegReadString (REGKEY_HKLM, "SOFTWARE\\AUXPANEL_TopPos", NULL, PanelTop, 10, (void *) &LastPos);
 if (Status != 0) 
  {
  ErrMsg = GetGeneralErrorString(Status);
  sprintf(buff,"Error setting the %s panel's Top position: %s", "Aux Panel", ErrMsg); 
  }
       // Save top
 LastPos = atoi(PanelTop);
     SetPanelAttribute (auxpanelHandle, ATTR_TOP, LastPos);
   
 Status = RegReadString (REGKEY_HKLM, "SOFTWARE\\AUXPANEL_LeftPos", NULL, PanelLeft, 10, (void *) &LastPos);
 if (Status != 0) 
   c {
  ErrMsg = GetGeneralErrorString(Status);
  sprintf(buff,"Error setting the %s panel's Left position: %s", "Aux Panel", ErrMsg); 
  }
 LastPos = atoi(PanelLeft);// Convert from string to integer
 SetPanelAttribute (auxpanelHandle, ATTR_LEFT, LastPos);

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Now, the question I have now is how to setup the registry keys so that it doesn't cause an error the first time it is installed and launched?

[daijoubu]

Here's a rough answer.  I left your code in red and put my new code in blue.  This still needs better error handling. 

Status = RegReadString (REGKEY_HKLM, "SOFTWARE\\AUXPANEL_TopPos", NULL, PanelTop, 10, (void *) &LastPos);
switch( Status )
{
  case 0:  // Everything is good, nothing to see here...
    break;

  case -5070:  // Reg Key does not exist.  Use default window position
    LastPos = DEFAULT_WINDOW_TOP_POSITION;
    break;

  default:  // An error occured!
    ErrMsg = GetGeneralErrorString(Status);
    sprintf(buff,"Error setting the %s panel's Top position: %s", "Aux Panel", ErrMsg); 
     break;
}

// This is bad.  Check the string length.  Make sure LastPos is assigned some value.
// Set top
LastPos = atoi(PanelTop);
SetPanelAttribute (auxpanelHandle, ATTR_TOP, LastPos);
  
The switch statement will let you handle specific errors.  As you use it twice, you should make it a separate function to ease maintenance. The error code returned if the registry key doesn't exist is -5070.  This is defined as ToolErr_MissingKey in toolbox.h.  You may want to also handle ToolErr_CantAccessKeyValue, ToolErr_MissingKeyValue and ToolErr_WrongKeyValueType. 

These two lines bother me:
LastPos = atoi(PanelTop);
SetPanelAttribute (auxpanelHandle, ATTR_TOP, LastPos);

In both versions, PanelTop may not be initialized.  In the debugger, this is ok as CVI initializes all memory to 0 for you.  In the runtime, these are random bits of memory.  the atoi function may find a value there.  As it might not be null terminated, it may find a very long sequence of numbers.  At least add this line to your error handling:
PanelTop[0] = 0;