NAME

       Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, Tcl_ExprObj - evaluate an expression

SYNOPSIS

       #include <tcl.h>

       int
       Tcl_ExprLongObj(interp, objPtr, longPtr)

       int
       Tcl_ExprDoubleObj(interp, objPtr, doublePtr)

       int
       Tcl_ExprBooleanObj(interp, objPtr, booleanPtr)

       int
       Tcl_ExprObj(interp, objPtr, resultPtrPtr)

ARGUMENTS

       Tcl_Interp *interp (in)                 Interpreter in whose context to evaluate objPtr.

       Tcl_Obj *objPtr (in)                    Pointer to an object containing the expression to evaluate.

       long *longPtr (out)                     Pointer  to  location  in which to store the integer value of the
                                               expression.

       int *doublePtr (out)                    Pointer to location in which to store the floating-point value of
                                               the expression.

       int *booleanPtr (out)                   Pointer to location in which to store the 0/1  boolean  value  of
                                               the expression.

       Tcl_Obj **resultPtrPtr (out)            Pointer  to  location  in  which to store a pointer to the object
                                               that is the result of the expression.
________________________________________________________________________________________________________________

DESCRIPTION

       These four procedures all evaluate an expression, returning the result in one of  four  different  forms.
       The  expression  is  given  by the objPtr argument, and it can have any of the forms accepted by the expr
       command.

       The interp argument refers to an interpreter used to evaluate the  expression  (e.g.  for  variables  and
       nested Tcl commands) and to return error information.

       For  all  of  these procedures the return value is a standard Tcl result: TCL_OK means the expression was
       successfully evaluated, and TCL_ERROR means that an error occurred while evaluating the  expression.   If
       TCL_ERROR  is  returned, then a message describing the error can be retrieved using Tcl_GetObjResult.  If
       an error occurs while executing a Tcl command  embedded  in  the  expression  then  that  error  will  be
       returned.

       If  the  expression is successfully evaluated, then its value is returned in one of four forms, depending
       on which procedure is invoked.  Tcl_ExprLongObj stores an integer value at *longPtr.  If the expression's
       actual value is a floating-point number, then it is truncated to an integer.  If the expression's  actual
       value is a non-numeric string then an error is returned.

       Tcl_ExprDoubleObj  stores  a  floating-point value at *doublePtr.  If the expression's actual value is an
       integer, it is converted to floating-point.  If the expression's actual value  is  a  non-numeric  string
       then an error is returned.

       Tcl_ExprBooleanObj  stores  a  0/1  integer value at *booleanPtr.  If the expression's actual value is an
       integer or floating-point number, then they store 0 at *booleanPtr if the value was zero and 1 otherwise.
       If the expression's actual value is a non-numeric string then it must be one of the  values  accepted  by
       Tcl_GetBoolean such as “yes” or “no”, or else an error occurs.

       If  Tcl_ExprObj  successfully  evaluates the expression, it stores a pointer to the Tcl object containing
       the expression's  value  at  *resultPtrPtr.   In  this  case,  the  caller  is  responsible  for  calling
       Tcl_DecrRefCount to decrement the object's reference count when it is finished with the object.

SEE ALSO

       Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString, Tcl_GetObjResult

KEYWORDS

       boolean, double, evaluate, expression, integer, object, string

Tcl                                                    8.0                                 Tcl_ExprLongObj(3tcl)