Tcl_ExprLong(3) 					      Tcl Library Procedures						   Tcl_ExprLong(3)

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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 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.
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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 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 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 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.
       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 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 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.  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.

SEE ALSO

       Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, Tcl_ExprObj

KEYWORDS

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

Tcl									7.0							   Tcl_ExprLong(3)