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OpenDarwin 7.2.1 - man page for tcl_exprlongobj (opendarwin section 3)

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Tcl_ExprLongObj(3)		      Tcl Library Procedures		       Tcl_ExprLongObj(3)

_________________________________________________________________________________________________

NAME
       Tcl_ExprLongObj,  Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, Tcl_ExprObj - evaluate an expres-
       sion

SYNOPSIS
       #include <tcl.h>

       int
       Tcl_ExprLongObj(interp, objPtr, longPtr)

       int
       Tcl_ExprDoubleObj(interp, objPtr, doublePtr)

       int
       Tcl_ExprBooleanObj(interp, objPtr, booleanPtr)

       int
       Tcl_ExprObj(interp, objPtr, resultPtrPtr)

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

       Tcl_Obj	    *objPtr	     (in)      Pointer	to an object containing the expression to
					       evaluate.

       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 float-
					       ing-point value of the expression.

       int	    *booleanPtr      (out)     Pointer to location in  which  to  store  the  0/1
					       boolean value of the expression.

       Tcl_Obj	    **resultPtrPtr   (out)     Pointer to location in which to store a pointer to
					       the object that is the result of the expression.
_________________________________________________________________

DESCRIPTION
       These four procedures all evaluate an expression, returning the result in one of four dif-
       ferent  forms.  The expression is given by the objPtr 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 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 a message describing the error
       can be retrieved using Tcl_GetObjResult.  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_ExprLongObj 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_ExprDoubleObj 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_ExprBooleanObj  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.

       If  Tcl_ExprObj	successfully  evaluates  the  expression,  it stores a pointer to the Tcl
       object containing the expression's value at *resultPtrPtr.  In this case,  the  caller  is
       responsible for calling Tcl_DecrRefCount to decrement the object's reference count when it
       is finished with the object.

SEE ALSO
       Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString, Tcl_GetObjResult

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

Tcl					       8.0			       Tcl_ExprLongObj(3)
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