'\"
'\" Copyright (c) 1996-1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: DoubleObj.3,v 1.4.8.1 2009/11/27 14:53:54 dkf Exp $
'\" 
.so man.macros
.TH Tcl_DoubleObj 3 8.0 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_NewDoubleObj, Tcl_SetDoubleObj, Tcl_GetDoubleFromObj \- manipulate Tcl objects as floating-point values
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
Tcl_Obj *
\fBTcl_NewDoubleObj\fR(\fIdoubleValue\fR)
.sp
\fBTcl_SetDoubleObj\fR(\fIobjPtr, doubleValue\fR)
.sp
int
\fBTcl_GetDoubleFromObj\fR(\fIinterp, objPtr, doublePtr\fR)
.SH ARGUMENTS
.AS Tcl_Interp doubleValue in/out
.AP double doubleValue in
A double-precision floating-point value used to initialize or set a Tcl object.
.AP Tcl_Obj *objPtr in/out
For \fBTcl_SetDoubleObj\fR, this points to the object in which to store a
double value.
For \fBTcl_GetDoubleFromObj\fR, this refers to the object
from which to retrieve a double value. 
.AP Tcl_Interp *interp in/out
When non-NULL, an error message is left here when double value retrieval fails.
.AP double *doublePtr out
Points to place to store the double value obtained from \fIobjPtr\fR.
.BE

.SH DESCRIPTION
.PP
These procedures are used to create, modify, and read Tcl objects that
hold double-precision floating-point values.
.PP
\fBTcl_NewDoubleObj\fR creates and returns a new Tcl object initialized to
the double value \fIdoubleValue\fR.  The returned Tcl object is unshared.
.PP
\fBTcl_SetDoubleObj\fR sets the value of an existing Tcl object pointed to
by \fIobjPtr\fR to the double value \fIdoubleValue\fR.  The \fIobjPtr\fR
argument must point to an unshared Tcl object.  Any attempt to set the value
of a shared Tcl object violates Tcl's copy-on-write policy.  Any existing
string representation or internal representation in the unshared Tcl object
will be freed as a consequence of setting the new value.
.PP
\fBTcl_GetDoubleFromObj\fR attempts to retrieve a double value from the
Tcl object \fIobjPtr\fR.  If the attempt succeeds, then \fBTCL_OK\fR is
returned, and the double value is written to the storage pointed to by
\fIdoublePtr\fR.  If the attempt fails, then \fBTCL_ERROR\fR is returned,
and if \fIinterp\fR is non-NULL, an error message is left in \fIinterp\fR.
The \fBTcl_ObjType\fR of \fIobjPtr\fR may be changed to make subsequent
calls to \fBTcl_GetDoubleFromObj\fR more efficient. 
'\" TODO: add discussion of treatment of NaN value
.SH "SEE ALSO"
Tcl_NewObj, Tcl_DecrRefCount, Tcl_IncrRefCount, Tcl_GetObjResult
.SH KEYWORDS
double, double object, double type, internal representation, object, object type, string representation