- NAME
- Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString —
evaluate an expression
- SYNOPSIS
- #include <tcl.h>
- int
- Tcl_ExprLong(interp, expr, longPtr)
- int
- Tcl_ExprDouble(interp, expr, doublePtr)
- int
- Tcl_ExprBoolean(interp, expr, booleanPtr)
- int
- Tcl_ExprString(interp, expr)
- ARGUMENTS
- DESCRIPTION
- SEE
ALSO
- KEYWORDS
Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString —
evaluate an expression
#include <tcl.h>
int
Tcl_ExprLong(interp, expr, longPtr)
int
Tcl_ExprDouble(interp, expr, doublePtr)
int
Tcl_ExprBoolean(interp, expr, booleanPtr)
int
Tcl_ExprString(interp, expr)
- Tcl_Interp *interp
(in)
- Interpreter in whose context to evaluate expr.
- const char *expr (in)
- Expression to be evaluated.
- 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.
These four procedures all evaluate the expression given by the
expr argument and return the result in one of four different
forms. The expression can have any of the forms accepted by the
expr command. Note that
these procedures have been largely replaced by the value-based
procedures Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, and
Tcl_ExprObj. Those
value-based procedures evaluate an expression held in a Tcl value
instead of a string. The value argument can retain an internal
representation that is more efficient to execute.
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 the
interpreter's result will hold a message describing the error. 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_ExprLong 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_ExprDouble 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_ExprBoolean 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.
Tcl_ExprString returns the value of the expression as a
string stored in the interpreter's result.
Tcl_ExprLongObj,
Tcl_ExprDoubleObj,
Tcl_ExprBooleanObj,
Tcl_ExprObj
boolean, double, evaluate, expression, integer, value, string
Copyright © 1989-1993 The Regents of the
University of California.
Copyright © 1994-1997 Sun Microsystems, Inc.