DOKK / manpages / debian 12 / tcl8.6-doc / Tcl_ExprObj.3tcl.en
Tcl_ExprLongObj(3tcl) Tcl Library Procedures Tcl_ExprLongObj(3tcl) 







Tcl_ExprLongObj, Tcl_ExprDoubleObj, Tcl_ExprBooleanObj,
    Tcl_ExprObj - evaluate an expression








#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)









  
Tcl_Interp *interp (in)

  
Interpreter in whose context to evaluate objPtr.

  
Tcl_Obj *objPtr (in)

  
Pointer to a value 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 value that is the
      result of the expression.
    
    

    

  










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 floating-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 value containing the expression's value at
    *resultPtrPtr. In this case, the caller is responsible for calling
    Tcl_DecrRefCount to decrement the value's reference count when it is
    finished with the value.










Tcl_ExprLong, Tcl_ExprDouble, Tcl_ExprBoolean, Tcl_ExprString,
    Tcl_GetObjResult










boolean, double, evaluate, expression, integer, value, string







  

    8.0
    Tcl