Страницы справочника OS X

Эта страница руководства является частью версии 5.0 Инструментов XCode

Читать страницы руководства

Tcl_ExprLong(3)                            Tcl Library Procedures                            Tcl_ExprLong(3)



____________________________________________________________________________________________________________

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
       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.
____________________________________________________________________________________________________________


DESCRIPTION
       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 object-based procedures Tcl_ExprLongObj,
       Tcl_ExprDoubleObj,  Tcl_ExprBooleanObj,  and  Tcl_ExprObj.  Those object-based procedures evaluate an
       expression held in a Tcl object instead of a string.  The object argument can retain an internal rep-resentation representation
       resentation 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 expres-sion. expression.
       sion.  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, depend-ing depending
       ing on which procedure is invoked.  Tcl_ExprLong stores an integer value at *longPtr.  If the expres-sion's expression's
       sion's actual value is a floating-point number, then it is truncated to an integer.  If  the  expres-sion's expression's
       sion'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 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.

       Tcl_ExprString returns the value of the expression as a string stored in the interpreter's result.


SEE ALSO
       Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, Tcl_ExprObj


KEYWORDS
       boolean, double, evaluate, expression, integer, object, string



Tcl                                                  7.0                                     Tcl_ExprLong(3)