Tcl_ExprLongObj(3)					      Tcl Library Procedures						Tcl_ExprLongObj(3)

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NAME

       Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, Tcl_ExprObj - evaluate an expression

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

       These  four  procedures	all  evaluate  an expression, returning the result in one of four different 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  float-
       ing-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 *resultP-
       trPtr.  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)