Tcl_ExprLongObj(3) Tcl Library Procedures 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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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 expres-sion. expression.
sion. If TCL_ERROR is returned, then a message describing the error can be retrieved using Tcl_GetO-bjResult. Tcl_GetObjResult.
bjResult. 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, depend-ing depending
ing 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 other-wise. otherwise.
wise. 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 contain-ing containing
ing 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(3)
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