Tcl_ExprLong man page on BSDi

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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, string, longPtr)

       int
       Tcl_ExprDouble(interp, string, doublePtr)

       int
       Tcl_ExprBoolean(interp, string, booleanPtr)

       int
       Tcl_ExprString(interp, string)

ARGUMENTS
       Tcl_Interp   *interp	  (in)	    Interpreter in  whose
					    context  to	 evaluate
					    string.

       char	    *string	  (in)	    Expression	 to    be
					    evaluated.	 Must  be
					    in	writable   memory
					    (the       expression
					    parser  makes  tempo-
					    rary modifications to
					    the	  string   during
					    parsing,   which   it
					    undoes before return-
					    ing).

       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			       7.0				1

Tcl_ExprLong(3)	      Tcl Library Procedures	  Tcl_ExprLong(3)

DESCRIPTION
       These four procedures all evaluate an expression,  return-
       ing  the	 result	 in  one  of  four  different forms.  The
       expression is given by the string  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 com-
       mands) and to return error information.	Interp->result is
       assumed to be initialized in the standard fashion when any
       of the procedures are invoked.

       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 interp->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 *dou-
       blePtr.	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  float-
       ing-point   number,   then  Tcl_ExprBoolean  stores  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  interp->result.   If	the  expression's
       actual value is an integer then Tcl_ExprString converts it
       to a string using sprintf with a ``%d'' converter.  If the
       expression's actual value is a floating-point number, then
       Tcl_ExprString calls Tcl_PrintDouble to convert	it  to	a
       string.

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

Tcl			       7.0				2

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