XmStringEmpty — A compound string function that provides information on the existence of non-zero-length

XmStringEmpty returns a Boolean value indicating whether any non-zero-length text components exist in the
       provided compound string.  It returns True if there are no text segments in the string. If  this  routine
       is passed NULL as the string, it returns True.

       s1        Specifies the compound string

XmStringEmpty  — A compound string function that provides information on the existence of non-zero-length
       text components "XmStringEmpty" "compound string functions" "XmStringEmpty"

XmStringCreate(3).

                                                                                                XmStringEmpty(3)

       Returns  True if there are no text segments in the string.  If this routine is passed NULL as the string,
       it returns True.

       #include <Xm/Xm.h>
       BooleanXmStringEmpty(
       XmStrings1);