XtOffset, XtOffsetOf, XtNumber - determine the byte offset or number of array elements
Specifies a fixed-size array.
Specifies the name of the field for which to calculate the
Specifies a type that is declared as a pointer to the structure.
Specifies a type that is declared as a structure.
The XtOffset macro is usually used to determine the offset of various resource fields from the beginning of a widget and can be used at compile time in static initializations.
The XtOffsetOf macro expands to a constant expression that gives the offset in bytes to the specified structure member from the beginning of the structure. It is normally used to statically initialize resource lists and is more portable than XtOffset, which serves the same function.
macro returns the number of elements
in the specified argument lists, resources lists, and other counted arrays.
X Toolkit Intrinsics -- C Language Interface
Xlib -- C Language X Interface