Tcl_ExprLongObj(3) Tcl (8.0) Tcl_ExprLongObj(3)
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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
string or 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.
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Tcl_ExprLongObj(3) Tcl (8.0) Tcl_ExprLongObj(3)
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
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Tcl_ExprLongObj(3) Tcl (8.0) Tcl_ExprLongObj(3)
KEYWORDS
boolean, double, evaluate, expression, integer, object,
string
Page 3 (printed 2/19/99)
