- 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
- DESCRIPTION
- REFERENCE
COUNT MANAGEMENT
- SEE
ALSO
- KEYWORDS
Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, Tcl_ExprObj
— evaluate an expression
#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)
- Tcl_Interp *interp (in)
- Interpreter in whose context to evaluate objPtr.
- Tcl_Obj *objPtr
(in)
- Pointer to a value 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 value
that is the result of the expression.
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 value containing the expression's value
at *resultPtrPtr. In this case, the caller is responsible
for calling Tcl_DecrRefCount to decrement the
value's reference count when it is finished with the value.
Tcl_ExprLongObj, Tcl_ExprDoubleObj,
Tcl_ExprBooleanObj, and Tcl_ExprObj all increment and
decrement the reference count of their objPtr arguments; you
must not pass them any value with a reference count of zero. They
also manipulate the interpreter result; you must not count on the
interpreter result to hold the reference count of any value over
these calls.
Tcl_ExprLong,
Tcl_ExprDouble,
Tcl_ExprBoolean,
Tcl_ExprString,
Tcl_GetObjResult
boolean, double, evaluate, expression, integer, value, string
Copyright © 1996-1997 Sun Microsystems,
Inc.