Manual Pages for UNIX Operating System command usage for man Tcl_ExprDouble

Tcl Library Procedures                         Tcl_ExprLong(3TCL)



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NAME
     Tcl_ExprLong,        Tcl_ExprDouble,        Tcl_ExprBoolean,
     Tcl_ExprString - evaluate an expression

SYNOPSIS
     #include 

     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.                  |

     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.
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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  expr command.  Note that these procedures



Tcl                     Last change: 7.0                        1






Tcl Library Procedures                         Tcl_ExprLong(3TCL)



     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  representation  that
     is more efficient to execute.

     The interp argument refers to an interpreter used to  evalu-
     ate  the  expression (e.g. for variables and nested Tcl com-
     mands) 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 pro-
     cedure 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 con-
     verted 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.


SEE ALSO
     Tcl_ExprLongObj,   Tcl_ExprDoubleObj,    Tcl_ExprBooleanObj,
     Tcl_ExprObj


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



Tcl                     Last change: 7.0                        2






Tcl Library Procedures                         Tcl_ExprLong(3TCL)



ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:

     _______________________________________
    |   ATTRIBUTE TYPE   |  ATTRIBUTE VALUE|
    |____________________|__________________|_
    | Availability       |  runtime/tcl-8  |
    |____________________|__________________|_
    | Interface Stability|  Uncommitted    |
    |____________________|_________________|

NOTES
     Source for Tcl is available on http://opensolaris.org.









































Tcl                     Last change: 7.0                        3