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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.
____________________________________________________________________________________________________________


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  com-mand. command.
       mand.  Note that these procedures have been largely replaced by the object-based procedures Tcl_Expr-LongObj, Tcl_ExprLongObj,
       LongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, and Tcl_ExprObj.  Those object-based procedures eval-uate evaluate
       uate  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  expres-sion. expression.
       sion.   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, depend-ing depending
       ing on which procedure is invoked.  Tcl_ExprLong stores an integer value at *longPtr.  If the expres-sion's expression's
       sion's  actual  value is a floating-point number, then it is truncated to an integer.  If the expres-sion's expression's
       sion'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 other-wise. otherwise.
       wise.  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)

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