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Tcl_ExprLong(3) Tcl Library Procedures Tcl_ExprLong(3) ________________________________________________________________________________ NAME Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString - evaluate an expression SYNOPSIS #include <tcl.h> int Tcl_ExprLong(interp, expr, longPtr) int Tcl_ExprDouble(interp, expr, doublePtr) int Tcl_ExprBoolean(interp, expr, booleanPtr) int Tcl_ExprString(interp, expr) ARGUMENTS Tcl_Interp *interp (in) Interpreter in whose context to evalu- ate expr. const char *expr (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 ex- pression. int *booleanPtr (out) Pointer to location in which to store the 0/1 boolean value of the expres- sion. ________________________________________________________________________________ DESCRIPTION These four procedures all evaluate the expression given by the expr argu- ment 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 value-based procedures Tcl_Ex- prLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, and Tcl_ExprObj. Those value-based procedures evaluate an expression held in a Tcl value instead of a string. The value argument can retain an internal representation that is more efficient to execute. The interp argument refers to an interpreter used to evaluate the expres- sion (e.g. for variables and nested Tcl commands) and to return error in- formation. 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 expres- 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 expres- sion'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 re- turned. Tcl_ExprBoolean stores a 0/1 integer value at *booleanPtr. If the expres- sion'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 expres- sion's actual value is a non-numeric string then it must be one of the val- ues accepted by Tcl_GetBoolean such as "yes" or "no", or else an error oc- curs. Tcl_ExprString returns the value of the expression as a string stored in the interpreter's result. SEE ALSO Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj, Tcl_ExprObj KEYWORDS boolean, double, evaluate, expression, integer, value, string Tcl 7.0 Tcl_ExprLong(3)
NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | SEE ALSO | KEYWORDS
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