- 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

int

int

int

int

- 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.

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.

Copyright © 1989-1993 The Regents of the
University of California.

Copyright © 1994-1997 Sun Microsystems, Inc.

Copyright © 1994-1997 Sun Microsystems, Inc.