Name	Class	Type	Default	Access
XmNgetValueProc	XmCGetValueProc	SpinboxGetValueProc	dynamic	CSG
XmNgetValueData	XmCGetValueData	XtPointer	NULL	CSG
XmNshowValueProc	XmCShowValueProc	SpinboxShowValueProc	dynamic	CSG
XmNshowValueData	XmCShowValueData	XtPointer	NULL	CSG

all of the built-in types have built-in get and show functions, so the user need not set them except when setting XmNspinboxType to XmSPINBOX_USER_DEFINED.

typedef Boolean (SpinboxGetValueProc) (
   Widget spinbox,
   XtPointer client_data,
   const char *buffer,
   size_t buffer_len,
   long *num );

1. the spinbox (Widget).
2. a user-defined pointer specified by XmNgetValueData. (XtPointer)
3. a buffer holding the value of the textfield. (const char *)
4. the length of the string in buffer. (size_t)
5. a long* to store the converted value (long*).

If the conversion is successful, it should return True. If it fails, it should return False. If the function fails, the value will not be set and the spinbox's XmNvalueChangedCallbacks will not be called.

As a basic example, if the get_value function for XmSPINBOX_NUMBER had no decimal places, it could read:

Boolean default_get_value (
   Widget w,
   XtPointer client_data,
   const char *buffer,
   size_t buflen,
   long *value )
{
   errno = 0;
   *value = strtol ( buffer, NULL, 10 );
   return ( !errno );
}

and the get_value function for XmSPINBOX_CLOCK might read

Boolean clock_get_value (
   Widget w,
   XtPointer client_data,
   const char *buffer,
   size_t buflen,
   int *value )
{
   long hr, min=0;
   char *pchar;
   errno = 0;
   hr = strtol ( buffer, &pchar, 10 );
   if ( *pchar=':' )
      min = strtol ( ++pchar, &pchar, 10 );
   *value = hr*60 + min;
   return ( !errno );

Note that the checks to see if the value is within XmNminimum and XmNmaximum are handled by the Spinbox widget, so the XmNgetValueProc doesn't need to check for that.

typedef void (SpinboxShowValueProc) (
   Widget spinbox,
   XtPointer client_data,
   long num,
   char *buffer,
   size_t maxlen );

1. the spinbox (Widget).
2. a user-defined pointer specified by XmNshowValueData. (XtPointer)
3. the value that needs to be converted to text for the textfield (long).
4. a buffer to store the converted value (char*).
5. the number of characters that buffer will hold, including zero terminator (size_t).

In practice, the maxlen will be no less than 128 characters, so space should never be a problem.

As an example, if the show_value function for XmSPINBOX_NUMBER had no decimal places, it might read:

void default_show_value (
   Widget w,
   XtPointer client_data,
   long value,
   char *buffer,
   size_t maxlen )
{
   (void) sprintf ( buffer "%ld", value );
}

and the show_value function for XmSPINBOX_CLOCK_HM might read:

void clock_show_value (
   Widget w,
   XtPointer client_data,
   long value,
   char *buffer,
   size_t maxlen )
{
   (void) sprintf ( buffer, "%02ld:%02ld", value/60, value%60 );
}