DOKK / manpages / debian 11 / tcl8.6-doc / Tcl_GetBooleanFromObj.3tcl.en
Tcl_BooleanObj(3tcl) Tcl Library Procedures Tcl_BooleanObj(3tcl) 







Tcl_NewBooleanObj, Tcl_SetBooleanObj, Tcl_GetBooleanFromObj -
    store/retrieve boolean value in a Tcl_Obj








#include <tcl.h>

Tcl_Obj *
Tcl_NewBooleanObj(boolValue)

Tcl_SetBooleanObj(objPtr, boolValue)

int
Tcl_GetBooleanFromObj(interp, objPtr, boolPtr)









  
int boolValue (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 retrieved, an error message is left in the
      interpreter's result value unless interp is NULL.

  
int *boolPtr (out)

  
Points to place where Tcl_GetBooleanFromObj stores the boolean
      value (0 or 1) obtained from objPtr.
    
    

    

  










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 boolValue 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 boolValue 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
    boolValue. 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 boolValue 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 address given by boolPtr. If objPtr holds
    any value recognized as a number by Tcl, then if that value is zero a 0 is
    written at the address given by boolPtr and if that value is non-zero
    a 1 is written at the address given by boolPtr. In all cases where a
    value is written at the address given by boolPtr,
    Tcl_GetBooleanFromObj returns TCL_OK. If the value of
    objPtr does not meet any of the conditions above, then
    TCL_ERROR is returned and an error message is left in the
    interpreter's result 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 efficiently.


Note that the routines Tcl_GetBooleanFromObj and
    Tcl_GetBoolean are not functional equivalents. The set of values for
    which Tcl_GetBooleanFromObj 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.










Tcl_NewObj, Tcl_IsShared, Tcl_GetBoolean










boolean, value







  

    8.5
    Tcl