- 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.