Tcl_ExprLong(3) Tcl Library Procedures Tcl_ExprLong(3)
Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString - evaluate an expression
Tcl_ExprLong(interp, string, longPtr)
Tcl_ExprDouble(interp, string, doublePtr)
Tcl_ExprBoolean(interp, string, booleanPtr)
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.
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
The interp argument refers to an interpreter used to evaluate the expression (e.g. for variables and nested Tcl commands) and to return
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
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.
Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, Tcl_ExprObj
boolean, double, evaluate, expression, integer, object, string
Tcl 7.0 Tcl_ExprLong(3)