TclExprLong(3) Tcl Library Procedures TclExprLong(3)

NAME
       TclExprLong,  TclExprDouble, TclExprBoolean, TclExprString - evalu-
       ate an expression

SYNOPSIS
       ##iinncclluuddee <>

       int
       TTccllEExxpprrLLoonngg(interp, string, longPtr)

       int
       TTccllEExxpprrDDoouubbllee(interp, string, doublePtr)

       int
       TTccllEExxpprrBBoooolleeaann(interp, string, booleanPtr)

       int
       TTccllEExxpprrSSttrriinngg(interp, string)

AARRGGUUMMEENNTTSS
       TclInterp   *interp       (in)      Interpreter in  whose  context  to
                                            evaluate string or objPtr.         |

       CONST                                                                   |
       char   *string       (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  string
       argument  and  return  the  result in one of four different forms.  The
       expression can have any of the forms  accepted  by  the  eexxpprr  command.
       Note  that  these  procedures have been largely replaced by the object-
       based   procedures   TTccllEExxpprrLLoonnggOObbjj,   TTccllEExxpprrDDoouubblleeOObbjj,    TTccllEExxpprr-
       BBoooolleeaannOObbjj, and TTccllEExxpprrOObbjj.  Those object-based procedures evaluate an
       expression held in a Tcl object instead of a string.  The object  argu-
       ment  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:
       TTCCLLOOKK  means  the expression was successfully evaluated, and TTCCLLEERRRROORR
       means that an error  occurred  while  evaluating  the  expression.   If
       TTCCLLEERRRROORR 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.
       TTccllEExxpprrLLoonngg  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.

       TTccllEExxpprrDDoouubbllee 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.

       TTccllEExxpprrBBoooolleeaann  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 TTccllGGeettBBoooolleeaann such as ``yes'' or ``no'',
       or else an error occurs.

       TTccllEExxpprrSSttrriinngg returns the value of the expression as a  string  stored
       in  the  interpreter's  result.  If the expression's actual value is an
       integer then TTccllEExxpprrSSttrriinngg converts it to a string using sspprriinnttff  with
       a  ``%d''  converter.   If the expression's actual value is a floating-
       point number, then TTccllEExxpprrSSttrriinngg calls TTccllPPrriinnttDDoouubbllee to  convert  it
       to a string.


SEE ALSO
       TclExprLongObj, TclExprDoubleObj, TclExprBooleanObj, TclExprObj


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



Tcl                                   7.0                      TclExprLong(3)