.\" $Xorg: XtOffset.man,v 1.4 2001/03/16 17:53:52 pookie Exp $
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.ds tk X Toolkit
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.TH XtOffset 3Xt "Release 6.6" "X Version 11" "XT FUNCTIONS"
.SH NAME
XtOffset, XtOffsetOf, XtNumber \- determine the byte offset or number of array elements
.SH SYNTAX
Cardinal XtOffset(\fIpointer_type\fP, \fIfield_name\fP)
.br
      Type \fIpointer_type\fP;
.br
      Field \fIfield_name\fP;
.LP
Cardinal XtOffsetOf(\fIstructure_type\fP, \fIfield_name\fP)
.br
      Type \fIstructure_type\fP;
.br
      Field \fIfield_name\fP;
.LP
Cardinal XtNumber(\fIarray\fP)
.br
      ArrayVariable \fIarray\fP;
.SH ARGUMENTS
.IP \fIarray\fP 1i
Specifies a fixed-size array.
.IP \fIfield_name\fP 1i
Specifies the name of the field for which to calculate the byte offset.
.IP \fIpointer_type\fP 1i
Specifies a type that is declared as a pointer to the structure.
.IP \fIstructure_type\fP 1i
Specifies a type that is declared as a structure.
.SH DESCRIPTION
The
.ZN 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.
.LP
The
.ZN XtOffsetOf
macro expands to a constant expression that gives the offset in bytes
to the specified structure member rom the beginning of the structure.
It is normally used to statically initialize resource lists and is more
portable than
.ZN XtOffset ,
which serves the same function.
.LP
The
.ZN XtNumber
macro returns the number of elements in the specified argument lists, 
resources lists, and other counted arrays.
.SH "SEE ALSO"
XtGetResourceList(3Xt),
XtSetArg(3Xt)
.br
\fI\*(xT\fP
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\fI\*(xL\fP