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Tcl_BooleanObj(3)	    Tcl	Library	Procedures	     Tcl_BooleanObj(3)

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NAME
       Tcl_NewBooleanObj, Tcl_SetBooleanObj, Tcl_GetBooleanFromObj - store/re-
       trieve boolean value in a Tcl_Obj

SYNOPSIS
       #include	<tcl.h>

       Tcl_Obj *
       Tcl_NewBooleanObj(intValue)

       Tcl_SetBooleanObj(objPtr, intValue)

       int
       Tcl_GetBooleanFromObj(interp, objPtr, intPtr)

ARGUMENTS
       int intValue (in)		 Integer  value	 to  be	 stored	 as  a
					 boolean value in a Tcl_Obj.

       Tcl_Obj *objPtr (in/out)		 Points	to the	Tcl_Obj	 in  which  to
					 store,	 or  from  which to retrieve a
					 boolean value.

       Tcl_Interp *interp (in/out)	 If a  boolean	value  cannot  be  re-
					 trieved,  an error message is left in
					 the interpreter's result value	unless
					 interp	is NULL.

       int *intPtr (out)		 Points	to place where Tcl_GetBoolean-
					 FromObj stores	the boolean  value  (0
					 or 1) obtained	from objPtr.
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DESCRIPTION
       These  procedures  are  used  to	pass boolean values to and from	Tcl as
       Tcl_Obj's.  When	storing	a boolean value	into a Tcl_Obj,	 any  non-zero
       integer	value  in intValue is taken to be the boolean value 1, and the
       integer value 0 is taken	to be the boolean value	0.

       Tcl_NewBooleanObj creates a new Tcl_Obj,	stores the boolean value  int-
       Value in	it, and	returns	a pointer to the new Tcl_Obj.  The new Tcl_Obj
       has reference count of zero.

       Tcl_SetBooleanObj accepts objPtr, a pointer to an existing Tcl_Obj, and
       stores  in  the	Tcl_Obj	*objPtr	the boolean value intValue.  This is a
       write operation on *objPtr, so objPtr must be  unshared.	  Attempts  to
       write  to  a shared Tcl_Obj will	panic.	A successful write of intValue
       into *objPtr implies the	freeing	of any former value stored in *objPtr.

       Tcl_GetBooleanFromObj attempts to retrieve a  boolean  value  from  the
       value  stored in	*objPtr.  If objPtr holds a string value recognized by
       Tcl_GetBoolean, then the	recognized boolean value is written at the ad-
       dress given by intPtr.  If objPtr holds any value recognized as a  num-
       ber  by	Tcl,  then if that value is zero a 0 is	written	at the address
       given by	intPtr and if that value is non-zero a 1 is written at the ad-
       dress given by intPtr.  In all cases where a value is  written  at  the
       address	given by intPtr, Tcl_GetBooleanFromObj returns TCL_OK.	If the
       value of	objPtr does not	meet any of the	conditions above, then TCL_ER-
       ROR is returned and an error message is left in the  interpreter's  re-
       sult  unless  interp  is	 NULL.	 Tcl_GetBooleanFromObj	may  also make
       changes to the internal fields of  *objPtr  so  that  future  calls  to
       Tcl_GetBooleanFromObj  on  the  same objPtr can be performed more effi-
       ciently.

       Note that the routines Tcl_GetBooleanFromObj and	Tcl_GetBoolean are not
       functional equivalents.	The set	of values for which Tcl_GetBooleanFro-
       mObj will return	TCL_OK is strictly larger than the set of  values  for
       which  Tcl_GetBoolean  will  do	the  same.  For	example, the value "5"
       passed to Tcl_GetBooleanFromObj will lead to a TCL_OK return  (and  the
       boolean	value  1),  while the same value passed	to Tcl_GetBoolean will
       lead to a TCL_ERROR return.

SEE ALSO
       Tcl_NewObj, Tcl_IsShared, Tcl_GetBoolean

KEYWORDS
       boolean,	value

Tcl				      8.5		     Tcl_BooleanObj(3)

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